* [PATCH] fix for spin lock bad magic on SiFive UART
@ 2020-05-06 19:26 Sagar Shrikant Kadam
2020-05-06 19:26 ` [PATCH] tty: serial: add missing spin_lock_init for " Sagar Shrikant Kadam
2020-05-06 23:12 ` [PATCH] fix for spin lock bad magic on " Atish Patra
0 siblings, 2 replies; 9+ messages in thread
From: Sagar Shrikant Kadam @ 2020-05-06 19:26 UTC (permalink / raw
To: gregkh, palmer
Cc: Atish.Patra, linux-riscv, Anup.Patel, Sagar Shrikant Kadam,
paul.walmsley
A bad magic spin lock error was observed on HiFive Unleashed
running 5.7-rc1+ linux kernel. The discussion is available here [1].
Thanks to Atish Patra <Atish.Patra@wdc.com> for reporting it.
Although spin locks are used within the driver to guard the critical
sections, we missed to initialise it this resulted in race condition
and raised a spin lock error as shown in log below.
This happens at the time of hand-off between sifive serial and earlycon
driver (one is enabled and another is disabled) on any random CPU.
[1]: http://lists.infradead.org/pipermail/linux-riscv/2020-May/009724.html
Error Log:
=============================================================
OpenSBI v0.7-31-gd626037
____ _____ ____ _____
/ __ \ / ____| _ \_ _|
| | | |_ __ ___ _ __ | (___ | |_) || |
| | | | '_ \ / _ \ '_ \ \___ \| _ < | |
| |__| | |_) | __/ | | |____) | |_) || |_
\____/| .__/ \___|_| |_|_____/|____/_____|
| |
|_|
Platform Name : SiFive Freedom U540
Platform HART Features : RV64ACDFIMSU
Platform HART Count : 4
Current HART ID : 1
Firmware Base : 0x80000000
Firmware Size : 100 KB
Runtime SBI Version : 0.2
MIDELEG : 0x0000000000000222
MEDELEG : 0x000000000000b109
PMP0 : 0x0000000080000000-0x000000008001ffff (A)
PMP1 : 0x0000000000000000-0x0000007fffffffff (A,R,W,X)
U-Boot 2020.07-rc1-00201-g24e3f96-dirty (May 05 2020 - 05:44:09 -0700)
CPU: rv64imafdc
Model: SiFive HiFive Unleashed A00
DRAM: 8 GiB
MMC: spi@10050000:mmc@0: 0
In: serial@10010000
Out: serial@10010000
Err: serial@10010000
Net: eth0: ethernet@10090000
Hit any key to stop autoboot: 0
=>
=> setenv bootargs "root=/dev/ram rw console=ttySIF0 earlycon=sbi"
=> mmc rescan ; fatload mmc 0:2 0x80200000 uImage
=> fatload mmc 0:2 0x82200000 hifive-unleashed-a00-.dtb
=> bootm 0x80200000 - 0x82200000
21413948 bytes read in 11434 ms (1.8 MiB/s)
7100 bytes read in 12 ms (577.1 KiB/s)
## Booting kernel from Legacy Image at 80200000 ...
Image Name: Linux
Image Type: RISC-V Linux Kernel Image (uncompressed)
Data Size: 21413884 Bytes = 20.4 MiB
Load Address: 80200000
Entry Point: 80200000
Verifying Checksum ... OK
## Flattened Device Tree blob at 82200000
Booting using the fdt blob at 0x82200000
Loading Kernel Image
Using Device Tree in place at 0000000082200000, end 0000000082204bbb
Starting kernel ...
[ 0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
[ 0.000000] Linux version 5.7.0-rc4-00001-g0319a09-dirty (sagark2@sifive.com) (gcc version 8.2.0 (Buildroot 2018.11-rc2-00003-ga0787e9), GNU ld (GNU Binutils) 2.31.1) #2 SMP Wed May 6 11:46:22 PDT 2020
[ 0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
[ 0.000000] printk: bootconsole [sbi0] enabled
[ 0.000000] initrd not found or empty - disabling initrd
[ 0.000000] Zone ranges:
[ 0.000000] DMA32 [mem 0x0000000080200000-0x00000000ffffffff]
[ 0.000000] Normal [mem 0x0000000100000000-0x000000027fffffff]
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000080200000-0x000000027fffffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000080200000-0x000000027fffffff]
[ 0.000000] software IO TLB: mapped [mem 0xfbfff000-0xfffff000] (64MB)
[ 0.000000] SBI specification v0.2 detected
[ 0.000000] SBI implementation ID=0x1 Version=0x7
[ 0.000000] SBI v0.2 TIME extension detected
[ 0.000000] SBI v0.2 IPI extension detected
[ 0.000000] SBI v0.2 RFENCE extension detected
[ 0.000000] SBI v0.2 HSM extension detected
[ 0.000000] CPU with hartid=0 is not available
[ 0.000000] CPU with hartid=0 is not available
[ 0.000000] elf_hwcap is 0x112d
[ 0.000000] percpu: Embedded 17 pages/cpu s31976 r8192 d29464 u69632
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 2067975
[ 0.000000] Kernel command line: root=/dev/ram rw console=ttySIF0 earlycon=sbi
[ 0.000000] Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes, linear)
[ 0.000000] Inode-cache hash table entries: 524288 (order: 10, 4194304 bytes, linear)
[ 0.000000] Sorting __ex_table...
[ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
[ 0.000000] Memory: 8172080K/8386560K available (6403K kernel code, 4268K rwdata, 4096K rodata, 4599K init, 317K bss, 214480K reserved, 0K cma-reserved)
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] fixmap : 0xffffffcefee00000 - 0xffffffceff000000 (2048 kB)
[ 0.000000] pci io : 0xffffffceff000000 - 0xffffffcf00000000 ( 16 MB)
[ 0.000000] vmemmap : 0xffffffcf00000000 - 0xffffffcfffffffff (4095 MB)
[ 0.000000] vmalloc : 0xffffffd000000000 - 0xffffffdfffffffff (65535 MB)
[ 0.000000] lowmem : 0xffffffe000000000 - 0xffffffe1ffe00000 (8190 MB)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
[ 0.000000] rcu: Hierarchical RCU implementation.
[ 0.000000] rcu: RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=4.
[ 0.000000] rcu: RCU debug extended QS entry/exit.
[ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
[ 0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=4
[ 0.000000] NR_IRQS: 0, nr_irqs: 0, preallocated irqs: 0
[ 0.000000] plic: mapped 53 interrupts with 4 handlers for 9 contexts.
[ 0.000000] riscv_timer_init_dt: Registering clocksource cpuid [0] hartid [1]
[ 0.000000] clocksource: riscv_clocksource: mask: 0xffffffffffffffff max_cycles: 0x1d854df40, max_idle_ns: 3526361616960 ns
[ 0.000006] sched_clock: 64 bits at 1000kHz, resolution 1000ns, wraps every 2199023255500ns
[ 0.008564] Console: colour dummy device 80x25
[ 0.012994] Calibrating delay loop (skipped), value calculated using timer frequency.. 2.00 BogoMIPS (lpj=4000)
[ 0.023105] pid_max: default: 32768 minimum: 301
[ 0.028307] Mount-cache hash table entries: 16384 (order: 5, 131072 bytes, linear)
[ 0.035768] Mountpoint-cache hash table entries: 16384 (order: 5, 131072 bytes, linear)
[ 0.045466] rcu: Hierarchical SRCU implementation.
[ 0.050232] smp: Bringing up secondary CPUs ...
[ 0.056183] smp: Brought up 1 node, 4 CPUs
[ 0.060951] devtmpfs: initialized
[ 0.065496] random: get_random_u32 called from bucket_table_alloc.isra.25+0x4e/0x160 with crng_init=0
[ 0.065883] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
[ 0.084236] futex hash table entries: 1024 (order: 4, 65536 bytes, linear)
[ 0.091933] NET: Registered protocol family 16
[ 0.112741] vgaarb: loaded
[ 0.115121] SCSI subsystem initialized
[ 0.119037] usbcore: registered new interface driver usbfs
[ 0.124200] usbcore: registered new interface driver hub
[ 0.129609] usbcore: registered new device driver usb
[ 0.135583] clocksource: Switched to clocksource riscv_clocksource
[ 0.149004] NET: Registered protocol family 2
[ 0.153401] tcp_listen_portaddr_hash hash table entries: 4096 (order: 5, 163840 bytes, linear)
[ 0.161940] TCP established hash table entries: 65536 (order: 7, 524288 bytes, linear)
[ 0.171373] TCP bind hash table entries: 65536 (order: 9, 2097152 bytes, linear)
[ 0.185358] TCP: Hash tables configured (established 65536 bind 65536)
[ 0.191727] UDP hash table entries: 4096 (order: 6, 393216 bytes, linear)
[ 0.199402] UDP-Lite hash table entries: 4096 (order: 6, 393216 bytes, linear)
[ 0.207489] NET: Registered protocol family 1
[ 0.211848] RPC: Registered named UNIX socket transport module.
[ 0.217162] RPC: Registered udp transport module.
[ 0.221929] RPC: Registered tcp transport module.
[ 0.226704] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.233222] PCI: CLS 0 bytes, default 64
[ 0.585553] workingset: timestamp_bits=62 max_order=21 bucket_order=0
[ 0.600753] NFS: Registering the id_resolver key type
[ 0.605171] Key type id_resolver registered
[ 0.609375] Key type id_legacy registered
[ 0.613468] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[ 0.620391] 9p: Installing v9fs 9p2000 file system support
[ 0.626200] NET: Registered protocol family 38
[ 0.630359] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252)
[ 0.637773] io scheduler mq-deadline registered
[ 0.642371] io scheduler kyber registered
[ 0.707353] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
[ 0.714231] 10010000.serial: ttySIF0 at MMIO 0x10010000 (irq = 1, base_baud = 0) is a SiFive UART v0
[ 0.722691] BUG: spinlock bad magic on CPU#3, swapper/0/1
[ 0.728140] lock: 0xffffffe1f63ae018, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
[ 0.736388] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.7.0-rc4-00001-g0319a09-dirty #2
[ 0.744456] Call Trace:
[ 0.746983] [<ffffffe0006024c6>] walk_stackframe+0x0/0xa4
[ 0.752448] [<ffffffe0006026ac>] show_stack+0x2a/0x34
[ 0.757577] [<ffffffe000869f68>] dump_stack+0x6a/0x84
[ 0.762701] [<ffffffe000643060>] spin_dump+0x68/0x74
[ 0.767730] [<ffffffe000642c80>] do_raw_spin_lock+0xb0/0xcc
[ 0.773379] [<ffffffe000c3f528>] _raw_spin_lock_irqsave+0x20/0x2c
[ 0.779538] [<ffffffe0008d9aec>] uart_add_one_port+0x2f6/0x406
[ 0.785441] [<ffffffe0008e3974>] sifive_serial_probe+0x184/0x270
[ 0.791527] [<ffffffe000a1323c>] platform_drv_probe+0x32/0x5e
[ 0.797335] [<ffffffe000a11a2e>] really_probe+0x9a/0x21e
[ 0.802719] [<ffffffe000a11cb4>] driver_probe_device+0x2e/0x88
[ 0.808623] [<ffffffe000a11e86>] device_driver_attach+0x4c/0x50
[ 0.814613] [<ffffffe000a11ec4>] __driver_attach+0x3a/0xac
[ 0.820170] [<ffffffe000a1002a>] bus_for_each_dev+0x4a/0x72
[ 0.825813] [<ffffffe000a1153a>] driver_attach+0x1a/0x22
[ 0.831196] [<ffffffe000a1106c>] bus_add_driver+0x192/0x198
[ 0.836840] [<ffffffe000a123b2>] driver_register+0x3a/0xd0
[ 0.842397] [<ffffffe000a13202>] __platform_driver_register+0x3a/0x42
[ 0.848911] [<ffffffe00001749c>] sifive_serial_init+0x30/0x50
[ 0.854730] [<ffffffe0006000d0>] do_one_initcall+0x50/0x15a
[ 0.860369] [<ffffffe000001c80>] kernel_init_freeable+0x16a/0x1de
[ 0.866533] [<ffffffe000c3ad3c>] kernel_init+0x12/0x118
[ 0.871830] [<ffffffe00060120a>] ret_from_exception+0x0/0xc
[ 0.877524] printk: console [ttySIF0] enabled
[ 0.877524] printk: console [ttySIF0] enabled
[ 0.886258] printk: bootconsole [sbi0] disabled
[ 0.886258] printk: bootconsole [sbi0] disabled
The kernel doesn't hang and boots to prompt.
===============================================================
Adding the missing spin_lock_init fixes the spinlock error. With the patch
the serial port is tested with basic sanity checks of baudrate change,
receive and transmit using:
Change baud rate : stty -F /dev/ttySIF0 9600
Recive mode : cat /dev/ttySIF0
Transmit mode : echo "Hello" > /dev/ttySIF0
Some of the relevant boot log:
=================================
[ 0.642457] io scheduler kyber registered
[ 0.704650] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
[ 0.711531] 10010000.serial: ttySIF0 at MMIO 0x10010000 (irq = 1, base_baud = 0) is a SiFive UART v0
[ 0.720013] printk: console [ttySIF0] enabled
[ 0.720013] printk: console [ttySIF0] enabled
[ 0.728755] printk: bootconsole [sbi0] disabled
[ 0.728755] printk: bootconsole [sbi0] disabled
[ 0.738182] 10011000.serial: ttySIF1 at MMIO 0x10011000 (irq = 10, base_baud = 0) is a SiFive UART v0
[ 0.747674] [drm] radeon kernel modesetting enabled.
[ 0.766381] loop: module loaded
Sagar Shrikant Kadam (1):
tty: serial: add missing spin_lock_init for SiFive UART
drivers/tty/serial/sifive.c | 1 +
1 file changed, 1 insertion(+)
--
2.7.4
^ permalink raw reply [flat|nested] 9+ messages in thread
* [PATCH] tty: serial: add missing spin_lock_init for SiFive UART
2020-05-06 19:26 [PATCH] fix for spin lock bad magic on SiFive UART Sagar Shrikant Kadam
@ 2020-05-06 19:26 ` Sagar Shrikant Kadam
2020-05-06 23:10 ` Atish Patra
2020-05-07 6:49 ` Greg KH
2020-05-06 23:12 ` [PATCH] fix for spin lock bad magic on " Atish Patra
1 sibling, 2 replies; 9+ messages in thread
From: Sagar Shrikant Kadam @ 2020-05-06 19:26 UTC (permalink / raw
To: gregkh, palmer
Cc: Atish.Patra, linux-riscv, Anup.Patel, Sagar Shrikant Kadam,
paul.walmsley
Uninitialised spin lock on sifive serial port (ssp) raised
a race condition and resulted in spin lock bad magic as
reported and discussed here [1]
Initialising the spin lock resolves the issue.
The fix is tested on HiFive Unleashed A00 board with Linux 5.7-rc4
and OpenSBI v0.7
[1] http://lists.infradead.org/pipermail/linux-riscv/2020-May/009713.html
Fixes: 45c054d0815b ("tty: serial: add driver for the SiFive UART")
Reported-by: Atish Patra <Atish.Patra@wdc.com>
Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
---
drivers/tty/serial/sifive.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index 13eadcb..b061bdb 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -989,6 +989,7 @@ static int sifive_serial_probe(struct platform_device *pdev)
ssp->clk = clk;
ssp->clk_notifier.notifier_call = sifive_serial_clk_notifier;
+ spin_lock_init(&ssp->port.lock);
r = clk_notifier_register(ssp->clk, &ssp->clk_notifier);
if (r) {
dev_err(&pdev->dev, "could not register clock notifier: %d\n",
--
2.7.4
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH] tty: serial: add missing spin_lock_init for SiFive UART
2020-05-06 19:26 ` [PATCH] tty: serial: add missing spin_lock_init for " Sagar Shrikant Kadam
@ 2020-05-06 23:10 ` Atish Patra
2020-05-07 3:34 ` Sagar Kadam
2020-05-07 6:49 ` Greg KH
1 sibling, 1 reply; 9+ messages in thread
From: Atish Patra @ 2020-05-06 23:10 UTC (permalink / raw
To: Sagar Shrikant Kadam
Cc: Greg Kroah-Hartman, Anup Patel, Atish Patra, Palmer Dabbelt,
Paul Walmsley, linux-riscv
On Wed, May 6, 2020 at 12:27 PM Sagar Shrikant Kadam
<sagar.kadam@sifive.com> wrote:
>
> Uninitialised spin lock on sifive serial port (ssp) raised
> a race condition and resulted in spin lock bad magic as
> reported and discussed here [1]
> Initialising the spin lock resolves the issue.
>
> The fix is tested on HiFive Unleashed A00 board with Linux 5.7-rc4
> and OpenSBI v0.7
>
> [1] http://lists.infradead.org/pipermail/linux-riscv/2020-May/009713.html
>
> Fixes: 45c054d0815b ("tty: serial: add driver for the SiFive UART")
> Reported-by: Atish Patra <Atish.Patra@wdc.com>
> Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
> ---
> drivers/tty/serial/sifive.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
> index 13eadcb..b061bdb 100644
> --- a/drivers/tty/serial/sifive.c
> +++ b/drivers/tty/serial/sifive.c
> @@ -989,6 +989,7 @@ static int sifive_serial_probe(struct platform_device *pdev)
> ssp->clk = clk;
> ssp->clk_notifier.notifier_call = sifive_serial_clk_notifier;
>
> + spin_lock_init(&ssp->port.lock);
> r = clk_notifier_register(ssp->clk, &ssp->clk_notifier);
> if (r) {
> dev_err(&pdev->dev, "could not register clock notifier: %d\n",
> --
> 2.7.4
>
>
Looks good. I have verified the fix on unleashed.
Tested-by: Atish Patra <atish.patra@wdc.com>
--
Regards,
Atish
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] fix for spin lock bad magic on SiFive UART
2020-05-06 19:26 [PATCH] fix for spin lock bad magic on SiFive UART Sagar Shrikant Kadam
2020-05-06 19:26 ` [PATCH] tty: serial: add missing spin_lock_init for " Sagar Shrikant Kadam
@ 2020-05-06 23:12 ` Atish Patra
2020-05-07 3:59 ` Sagar Kadam
1 sibling, 1 reply; 9+ messages in thread
From: Atish Patra @ 2020-05-06 23:12 UTC (permalink / raw
To: Sagar Shrikant Kadam
Cc: Greg Kroah-Hartman, Anup Patel, Atish Patra, Palmer Dabbelt,
Paul Walmsley, linux-riscv
On Wed, May 6, 2020 at 12:27 PM Sagar Shrikant Kadam
<sagar.kadam@sifive.com> wrote:
>
> A bad magic spin lock error was observed on HiFive Unleashed
> running 5.7-rc1+ linux kernel. The discussion is available here [1].
> Thanks to Atish Patra <Atish.Patra@wdc.com> for reporting it.
>
> Although spin locks are used within the driver to guard the critical
> sections, we missed to initialise it this resulted in race condition
> and raised a spin lock error as shown in log below.
>
> This happens at the time of hand-off between sifive serial and earlycon
> driver (one is enabled and another is disabled) on any random CPU.
>
> [1]: http://lists.infradead.org/pipermail/linux-riscv/2020-May/009724.html
>
> Error Log:
> =============================================================
> OpenSBI v0.7-31-gd626037
> ____ _____ ____ _____
> / __ \ / ____| _ \_ _|
> | | | |_ __ ___ _ __ | (___ | |_) || |
> | | | | '_ \ / _ \ '_ \ \___ \| _ < | |
> | |__| | |_) | __/ | | |____) | |_) || |_
> \____/| .__/ \___|_| |_|_____/|____/_____|
> | |
> |_|
>
> Platform Name : SiFive Freedom U540
> Platform HART Features : RV64ACDFIMSU
> Platform HART Count : 4
> Current HART ID : 1
> Firmware Base : 0x80000000
> Firmware Size : 100 KB
> Runtime SBI Version : 0.2
>
> MIDELEG : 0x0000000000000222
> MEDELEG : 0x000000000000b109
> PMP0 : 0x0000000080000000-0x000000008001ffff (A)
> PMP1 : 0x0000000000000000-0x0000007fffffffff (A,R,W,X)
>
>
> U-Boot 2020.07-rc1-00201-g24e3f96-dirty (May 05 2020 - 05:44:09 -0700)
>
> CPU: rv64imafdc
> Model: SiFive HiFive Unleashed A00
> DRAM: 8 GiB
> MMC: spi@10050000:mmc@0: 0
> In: serial@10010000
> Out: serial@10010000
> Err: serial@10010000
> Net: eth0: ethernet@10090000
> Hit any key to stop autoboot: 0
> =>
> => setenv bootargs "root=/dev/ram rw console=ttySIF0 earlycon=sbi"
> => mmc rescan ; fatload mmc 0:2 0x80200000 uImage
> => fatload mmc 0:2 0x82200000 hifive-unleashed-a00-.dtb
> => bootm 0x80200000 - 0x82200000
> 21413948 bytes read in 11434 ms (1.8 MiB/s)
> 7100 bytes read in 12 ms (577.1 KiB/s)
> ## Booting kernel from Legacy Image at 80200000 ...
> Image Name: Linux
> Image Type: RISC-V Linux Kernel Image (uncompressed)
> Data Size: 21413884 Bytes = 20.4 MiB
> Load Address: 80200000
> Entry Point: 80200000
> Verifying Checksum ... OK
> ## Flattened Device Tree blob at 82200000
> Booting using the fdt blob at 0x82200000
> Loading Kernel Image
> Using Device Tree in place at 0000000082200000, end 0000000082204bbb
>
> Starting kernel ...
>
> [ 0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
> [ 0.000000] Linux version 5.7.0-rc4-00001-g0319a09-dirty (sagark2@sifive.com) (gcc version 8.2.0 (Buildroot 2018.11-rc2-00003-ga0787e9), GNU ld (GNU Binutils) 2.31.1) #2 SMP Wed May 6 11:46:22 PDT 2020
> [ 0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
> [ 0.000000] printk: bootconsole [sbi0] enabled
> [ 0.000000] initrd not found or empty - disabling initrd
> [ 0.000000] Zone ranges:
> [ 0.000000] DMA32 [mem 0x0000000080200000-0x00000000ffffffff]
> [ 0.000000] Normal [mem 0x0000000100000000-0x000000027fffffff]
> [ 0.000000] Movable zone start for each node
> [ 0.000000] Early memory node ranges
> [ 0.000000] node 0: [mem 0x0000000080200000-0x000000027fffffff]
> [ 0.000000] Initmem setup node 0 [mem 0x0000000080200000-0x000000027fffffff]
> [ 0.000000] software IO TLB: mapped [mem 0xfbfff000-0xfffff000] (64MB)
> [ 0.000000] SBI specification v0.2 detected
> [ 0.000000] SBI implementation ID=0x1 Version=0x7
> [ 0.000000] SBI v0.2 TIME extension detected
> [ 0.000000] SBI v0.2 IPI extension detected
> [ 0.000000] SBI v0.2 RFENCE extension detected
> [ 0.000000] SBI v0.2 HSM extension detected
> [ 0.000000] CPU with hartid=0 is not available
> [ 0.000000] CPU with hartid=0 is not available
> [ 0.000000] elf_hwcap is 0x112d
> [ 0.000000] percpu: Embedded 17 pages/cpu s31976 r8192 d29464 u69632
> [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 2067975
> [ 0.000000] Kernel command line: root=/dev/ram rw console=ttySIF0 earlycon=sbi
> [ 0.000000] Dentry cache hash table entries: 1048576 (order: 11, 8388608 bytes, linear)
> [ 0.000000] Inode-cache hash table entries: 524288 (order: 10, 4194304 bytes, linear)
> [ 0.000000] Sorting __ex_table...
> [ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
> [ 0.000000] Memory: 8172080K/8386560K available (6403K kernel code, 4268K rwdata, 4096K rodata, 4599K init, 317K bss, 214480K reserved, 0K cma-reserved)
> [ 0.000000] Virtual kernel memory layout:
> [ 0.000000] fixmap : 0xffffffcefee00000 - 0xffffffceff000000 (2048 kB)
> [ 0.000000] pci io : 0xffffffceff000000 - 0xffffffcf00000000 ( 16 MB)
> [ 0.000000] vmemmap : 0xffffffcf00000000 - 0xffffffcfffffffff (4095 MB)
> [ 0.000000] vmalloc : 0xffffffd000000000 - 0xffffffdfffffffff (65535 MB)
> [ 0.000000] lowmem : 0xffffffe000000000 - 0xffffffe1ffe00000 (8190 MB)
> [ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
> [ 0.000000] rcu: Hierarchical RCU implementation.
> [ 0.000000] rcu: RCU restricting CPUs from NR_CPUS=8 to nr_cpu_ids=4.
> [ 0.000000] rcu: RCU debug extended QS entry/exit.
> [ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies.
> [ 0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=4
> [ 0.000000] NR_IRQS: 0, nr_irqs: 0, preallocated irqs: 0
> [ 0.000000] plic: mapped 53 interrupts with 4 handlers for 9 contexts.
> [ 0.000000] riscv_timer_init_dt: Registering clocksource cpuid [0] hartid [1]
> [ 0.000000] clocksource: riscv_clocksource: mask: 0xffffffffffffffff max_cycles: 0x1d854df40, max_idle_ns: 3526361616960 ns
> [ 0.000006] sched_clock: 64 bits at 1000kHz, resolution 1000ns, wraps every 2199023255500ns
> [ 0.008564] Console: colour dummy device 80x25
> [ 0.012994] Calibrating delay loop (skipped), value calculated using timer frequency.. 2.00 BogoMIPS (lpj=4000)
> [ 0.023105] pid_max: default: 32768 minimum: 301
> [ 0.028307] Mount-cache hash table entries: 16384 (order: 5, 131072 bytes, linear)
> [ 0.035768] Mountpoint-cache hash table entries: 16384 (order: 5, 131072 bytes, linear)
> [ 0.045466] rcu: Hierarchical SRCU implementation.
> [ 0.050232] smp: Bringing up secondary CPUs ...
> [ 0.056183] smp: Brought up 1 node, 4 CPUs
> [ 0.060951] devtmpfs: initialized
> [ 0.065496] random: get_random_u32 called from bucket_table_alloc.isra.25+0x4e/0x160 with crng_init=0
> [ 0.065883] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
> [ 0.084236] futex hash table entries: 1024 (order: 4, 65536 bytes, linear)
> [ 0.091933] NET: Registered protocol family 16
> [ 0.112741] vgaarb: loaded
> [ 0.115121] SCSI subsystem initialized
> [ 0.119037] usbcore: registered new interface driver usbfs
> [ 0.124200] usbcore: registered new interface driver hub
> [ 0.129609] usbcore: registered new device driver usb
> [ 0.135583] clocksource: Switched to clocksource riscv_clocksource
> [ 0.149004] NET: Registered protocol family 2
> [ 0.153401] tcp_listen_portaddr_hash hash table entries: 4096 (order: 5, 163840 bytes, linear)
> [ 0.161940] TCP established hash table entries: 65536 (order: 7, 524288 bytes, linear)
> [ 0.171373] TCP bind hash table entries: 65536 (order: 9, 2097152 bytes, linear)
> [ 0.185358] TCP: Hash tables configured (established 65536 bind 65536)
> [ 0.191727] UDP hash table entries: 4096 (order: 6, 393216 bytes, linear)
> [ 0.199402] UDP-Lite hash table entries: 4096 (order: 6, 393216 bytes, linear)
> [ 0.207489] NET: Registered protocol family 1
> [ 0.211848] RPC: Registered named UNIX socket transport module.
> [ 0.217162] RPC: Registered udp transport module.
> [ 0.221929] RPC: Registered tcp transport module.
> [ 0.226704] RPC: Registered tcp NFSv4.1 backchannel transport module.
> [ 0.233222] PCI: CLS 0 bytes, default 64
> [ 0.585553] workingset: timestamp_bits=62 max_order=21 bucket_order=0
> [ 0.600753] NFS: Registering the id_resolver key type
> [ 0.605171] Key type id_resolver registered
> [ 0.609375] Key type id_legacy registered
> [ 0.613468] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
> [ 0.620391] 9p: Installing v9fs 9p2000 file system support
> [ 0.626200] NET: Registered protocol family 38
> [ 0.630359] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 252)
> [ 0.637773] io scheduler mq-deadline registered
> [ 0.642371] io scheduler kyber registered
> [ 0.707353] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
> [ 0.714231] 10010000.serial: ttySIF0 at MMIO 0x10010000 (irq = 1, base_baud = 0) is a SiFive UART v0
> [ 0.722691] BUG: spinlock bad magic on CPU#3, swapper/0/1
> [ 0.728140] lock: 0xffffffe1f63ae018, .magic: 00000000, .owner: <none>/-1, .owner_cpu: 0
> [ 0.736388] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.7.0-rc4-00001-g0319a09-dirty #2
> [ 0.744456] Call Trace:
> [ 0.746983] [<ffffffe0006024c6>] walk_stackframe+0x0/0xa4
> [ 0.752448] [<ffffffe0006026ac>] show_stack+0x2a/0x34
> [ 0.757577] [<ffffffe000869f68>] dump_stack+0x6a/0x84
> [ 0.762701] [<ffffffe000643060>] spin_dump+0x68/0x74
> [ 0.767730] [<ffffffe000642c80>] do_raw_spin_lock+0xb0/0xcc
> [ 0.773379] [<ffffffe000c3f528>] _raw_spin_lock_irqsave+0x20/0x2c
> [ 0.779538] [<ffffffe0008d9aec>] uart_add_one_port+0x2f6/0x406
> [ 0.785441] [<ffffffe0008e3974>] sifive_serial_probe+0x184/0x270
> [ 0.791527] [<ffffffe000a1323c>] platform_drv_probe+0x32/0x5e
> [ 0.797335] [<ffffffe000a11a2e>] really_probe+0x9a/0x21e
> [ 0.802719] [<ffffffe000a11cb4>] driver_probe_device+0x2e/0x88
> [ 0.808623] [<ffffffe000a11e86>] device_driver_attach+0x4c/0x50
> [ 0.814613] [<ffffffe000a11ec4>] __driver_attach+0x3a/0xac
> [ 0.820170] [<ffffffe000a1002a>] bus_for_each_dev+0x4a/0x72
> [ 0.825813] [<ffffffe000a1153a>] driver_attach+0x1a/0x22
> [ 0.831196] [<ffffffe000a1106c>] bus_add_driver+0x192/0x198
> [ 0.836840] [<ffffffe000a123b2>] driver_register+0x3a/0xd0
> [ 0.842397] [<ffffffe000a13202>] __platform_driver_register+0x3a/0x42
> [ 0.848911] [<ffffffe00001749c>] sifive_serial_init+0x30/0x50
> [ 0.854730] [<ffffffe0006000d0>] do_one_initcall+0x50/0x15a
> [ 0.860369] [<ffffffe000001c80>] kernel_init_freeable+0x16a/0x1de
> [ 0.866533] [<ffffffe000c3ad3c>] kernel_init+0x12/0x118
> [ 0.871830] [<ffffffe00060120a>] ret_from_exception+0x0/0xc
> [ 0.877524] printk: console [ttySIF0] enabled
> [ 0.877524] printk: console [ttySIF0] enabled
> [ 0.886258] printk: bootconsole [sbi0] disabled
> [ 0.886258] printk: bootconsole [sbi0] disabled
>
> The kernel doesn't hang and boots to prompt.
>
> ===============================================================
>
> Adding the missing spin_lock_init fixes the spinlock error. With the patch
> the serial port is tested with basic sanity checks of baudrate change,
> receive and transmit using:
>
> Change baud rate : stty -F /dev/ttySIF0 9600
> Recive mode : cat /dev/ttySIF0
> Transmit mode : echo "Hello" > /dev/ttySIF0
>
> Some of the relevant boot log:
> =================================
> [ 0.642457] io scheduler kyber registered
> [ 0.704650] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
> [ 0.711531] 10010000.serial: ttySIF0 at MMIO 0x10010000 (irq = 1, base_baud = 0) is a SiFive UART v0
> [ 0.720013] printk: console [ttySIF0] enabled
> [ 0.720013] printk: console [ttySIF0] enabled
> [ 0.728755] printk: bootconsole [sbi0] disabled
> [ 0.728755] printk: bootconsole [sbi0] disabled
> [ 0.738182] 10011000.serial: ttySIF1 at MMIO 0x10011000 (irq = 10, base_baud = 0) is a SiFive UART v0
> [ 0.747674] [drm] radeon kernel modesetting enabled.
> [ 0.766381] loop: module loaded
>
>
> Sagar Shrikant Kadam (1):
> tty: serial: add missing spin_lock_init for SiFive UART
>
> drivers/tty/serial/sifive.c | 1 +
> 1 file changed, 1 insertion(+)
>
> --
> 2.7.4
>
>
Just for future reference:
This should be sent as a part of the series (PATCH 0/1) as this is a
cover letter for the series.
--
Regards,
Atish
^ permalink raw reply [flat|nested] 9+ messages in thread
* RE: [PATCH] tty: serial: add missing spin_lock_init for SiFive UART
2020-05-06 23:10 ` Atish Patra
@ 2020-05-07 3:34 ` Sagar Kadam
0 siblings, 0 replies; 9+ messages in thread
From: Sagar Kadam @ 2020-05-07 3:34 UTC (permalink / raw
To: Atish Patra
Cc: Greg Kroah-Hartman, Anup Patel, Atish Patra, Palmer Dabbelt,
Paul Walmsley, linux-riscv
HI Atish,
> -----Original Message-----
> From: Atish Patra <atishp@atishpatra.org>
> Sent: Thursday, May 7, 2020 4:41 AM
> To: Sagar Kadam <sagar.kadam@sifive.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>; Palmer Dabbelt
> <palmer@dabbelt.com>; Atish Patra <Atish.Patra@wdc.com>; linux-riscv
> <linux-riscv@lists.infradead.org>; Anup Patel <Anup.Patel@wdc.com>; Paul
> Walmsley <paul.walmsley@sifive.com>
> Subject: Re: [PATCH] tty: serial: add missing spin_lock_init for SiFive UART
>
> [External Email] Do not click links or attachments unless you recognize the
> sender and know the content is safe
>
> On Wed, May 6, 2020 at 12:27 PM Sagar Shrikant Kadam
> <sagar.kadam@sifive.com> wrote:
> >
> > Uninitialised spin lock on sifive serial port (ssp) raised a race
> > condition and resulted in spin lock bad magic as reported and
> > discussed here [1] Initialising the spin lock resolves the issue.
> >
> > The fix is tested on HiFive Unleashed A00 board with Linux 5.7-rc4 and
> > OpenSBI v0.7
> >
> > [1]
> > http://lists.infradead.org/pipermail/linux-riscv/2020-May/009713.html
> >
> > Fixes: 45c054d0815b ("tty: serial: add driver for the SiFive UART")
> > Reported-by: Atish Patra <Atish.Patra@wdc.com>
> > Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
> > ---
> > drivers/tty/serial/sifive.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
> > index 13eadcb..b061bdb 100644
> > --- a/drivers/tty/serial/sifive.c
> > +++ b/drivers/tty/serial/sifive.c
> > @@ -989,6 +989,7 @@ static int sifive_serial_probe(struct
> platform_device *pdev)
> > ssp->clk = clk;
> > ssp->clk_notifier.notifier_call = sifive_serial_clk_notifier;
> >
> > + spin_lock_init(&ssp->port.lock);
> > r = clk_notifier_register(ssp->clk, &ssp->clk_notifier);
> > if (r) {
> > dev_err(&pdev->dev, "could not register clock
> > notifier: %d\n",
> > --
> > 2.7.4
> >
> >
>
> Looks good. I have verified the fix on unleashed.
>
> Tested-by: Atish Patra <atish.patra@wdc.com>
>
Thanks for testing the patch, and confirming that it's fixed.
BR,
Sagar Kadam
> --
> Regards,
> Atish
^ permalink raw reply [flat|nested] 9+ messages in thread
* RE: [PATCH] fix for spin lock bad magic on SiFive UART
2020-05-06 23:12 ` [PATCH] fix for spin lock bad magic on " Atish Patra
@ 2020-05-07 3:59 ` Sagar Kadam
0 siblings, 0 replies; 9+ messages in thread
From: Sagar Kadam @ 2020-05-07 3:59 UTC (permalink / raw
To: Atish Patra
Cc: Greg Kroah-Hartman, Anup Patel, Atish Patra, Palmer Dabbelt,
Paul Walmsley, linux-riscv
Hi Atish,
> -----Original Message-----
> From: Atish Patra <atishp@atishpatra.org>
> Sent: Thursday, May 7, 2020 4:43 AM
> To: Sagar Kadam <sagar.kadam@sifive.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>; Palmer Dabbelt
> <palmer@dabbelt.com>; Atish Patra <Atish.Patra@wdc.com>; linux-riscv
> <linux-riscv@lists.infradead.org>; Anup Patel <Anup.Patel@wdc.com>; Paul
> Walmsley <paul.walmsley@sifive.com>
> Subject: Re: [PATCH] fix for spin lock bad magic on SiFive UART
>
> [External Email] Do not click links or attachments unless you recognize the
> sender and know the content is safe
>
> On Wed, May 6, 2020 at 12:27 PM Sagar Shrikant Kadam
> <sagar.kadam@sifive.com> wrote:
> >
> > A bad magic spin lock error was observed on HiFive Unleashed running
> > 5.7-rc1+ linux kernel. The discussion is available here [1].
> > Thanks to Atish Patra <Atish.Patra@wdc.com> for reporting it.
> >
> > Although spin locks are used within the driver to guard the critical
> > sections, we missed to initialise it this resulted in race condition
> > and raised a spin lock error as shown in log below.
> >
> > This happens at the time of hand-off between sifive serial and
> > earlycon driver (one is enabled and another is disabled) on any random
> CPU.
> >
> > [1]:
> > http://lists.infradead.org/pipermail/linux-riscv/2020-May/009724.html
> >
> > Error Log:
> > =============================================================
> > OpenSBI v0.7-31-gd626037
> > ____ _____ ____ _____
> > / __ \ / ____| _ \_ _|
> > | | | |_ __ ___ _ __ | (___ | |_) || |
> > | | | | '_ \ / _ \ '_ \ \___ \| _ < | | | |__| | |_) | __/ | |
> > |____) | |_) || |_
> > \____/| .__/ \___|_| |_|_____/|____/_____|
> > | |
> > |_|
> >
> > Platform Name : SiFive Freedom U540
> > Platform HART Features : RV64ACDFIMSU
> > Platform HART Count : 4
> > Current HART ID : 1
> > Firmware Base : 0x80000000
> > Firmware Size : 100 KB
> > Runtime SBI Version : 0.2
> >
> > MIDELEG : 0x0000000000000222
> > MEDELEG : 0x000000000000b109
> > PMP0 : 0x0000000080000000-0x000000008001ffff (A)
> > PMP1 : 0x0000000000000000-0x0000007fffffffff (A,R,W,X)
> >
> >
> > U-Boot 2020.07-rc1-00201-g24e3f96-dirty (May 05 2020 - 05:44:09 -0700)
> >
> > CPU: rv64imafdc
> > Model: SiFive HiFive Unleashed A00
> > DRAM: 8 GiB
> > MMC: spi@10050000:mmc@0: 0
> > In: serial@10010000
> > Out: serial@10010000
> > Err: serial@10010000
> > Net: eth0: ethernet@10090000
> > Hit any key to stop autoboot: 0
> > =>
> > => setenv bootargs "root=/dev/ram rw console=ttySIF0 earlycon=sbi"
> > => mmc rescan ; fatload mmc 0:2 0x80200000 uImage => fatload mmc 0:2
> > 0x82200000 hifive-unleashed-a00-.dtb => bootm 0x80200000 -
> 0x82200000
> > 21413948 bytes read in 11434 ms (1.8 MiB/s)
> > 7100 bytes read in 12 ms (577.1 KiB/s) ## Booting kernel from Legacy
> > Image at 80200000 ...
> > Image Name: Linux
> > Image Type: RISC-V Linux Kernel Image (uncompressed)
> > Data Size: 21413884 Bytes = 20.4 MiB
> > Load Address: 80200000
> > Entry Point: 80200000
> > Verifying Checksum ... OK
> > ## Flattened Device Tree blob at 82200000
> > Booting using the fdt blob at 0x82200000
> > Loading Kernel Image
> > Using Device Tree in place at 0000000082200000, end
> > 0000000082204bbb
> >
> > Starting kernel ...
> >
> > [ 0.000000] OF: fdt: Ignoring memory range 0x80000000 - 0x80200000
> > [ 0.000000] Linux version 5.7.0-rc4-00001-g0319a09-dirty
> (sagark2@sifive.com) (gcc version 8.2.0 (Buildroot 2018.11-rc2-00003-
> ga0787e9), GNU ld (GNU Binutils) 2.31.1) #2 SMP Wed May 6 11:46:22 PDT
> 2020
> > [ 0.000000] earlycon: sbi0 at I/O port 0x0 (options '')
> > [ 0.000000] printk: bootconsole [sbi0] enabled
> > [ 0.000000] initrd not found or empty - disabling initrd
> > [ 0.000000] Zone ranges:
> > [ 0.000000] DMA32 [mem 0x0000000080200000-0x00000000ffffffff]
> > [ 0.000000] Normal [mem 0x0000000100000000-0x000000027fffffff]
> > [ 0.000000] Movable zone start for each node
> > [ 0.000000] Early memory node ranges
> > [ 0.000000] node 0: [mem 0x0000000080200000-0x000000027fffffff]
> > [ 0.000000] Initmem setup node 0 [mem 0x0000000080200000-
> 0x000000027fffffff]
> > [ 0.000000] software IO TLB: mapped [mem 0xfbfff000-0xfffff000] (64MB)
> > [ 0.000000] SBI specification v0.2 detected
> > [ 0.000000] SBI implementation ID=0x1 Version=0x7
> > [ 0.000000] SBI v0.2 TIME extension detected
> > [ 0.000000] SBI v0.2 IPI extension detected
> > [ 0.000000] SBI v0.2 RFENCE extension detected
> > [ 0.000000] SBI v0.2 HSM extension detected
> > [ 0.000000] CPU with hartid=0 is not available
> > [ 0.000000] CPU with hartid=0 is not available
> > [ 0.000000] elf_hwcap is 0x112d
> > [ 0.000000] percpu: Embedded 17 pages/cpu s31976 r8192 d29464
> u69632
> > [ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 2067975
> > [ 0.000000] Kernel command line: root=/dev/ram rw console=ttySIF0
> earlycon=sbi
> > [ 0.000000] Dentry cache hash table entries: 1048576 (order: 11,
> 8388608 bytes, linear)
> > [ 0.000000] Inode-cache hash table entries: 524288 (order: 10, 4194304
> bytes, linear)
> > [ 0.000000] Sorting __ex_table...
> > [ 0.000000] mem auto-init: stack:off, heap alloc:off, heap free:off
> > [ 0.000000] Memory: 8172080K/8386560K available (6403K kernel code,
> 4268K rwdata, 4096K rodata, 4599K init, 317K bss, 214480K reserved, 0K
> cma-reserved)
> > [ 0.000000] Virtual kernel memory layout:
> > [ 0.000000] fixmap : 0xffffffcefee00000 - 0xffffffceff000000 (2048 kB)
> > [ 0.000000] pci io : 0xffffffceff000000 - 0xffffffcf00000000 ( 16 MB)
> > [ 0.000000] vmemmap : 0xffffffcf00000000 - 0xffffffcfffffffff (4095 MB)
> > [ 0.000000] vmalloc : 0xffffffd000000000 - 0xffffffdfffffffff (65535 MB)
> > [ 0.000000] lowmem : 0xffffffe000000000 - 0xffffffe1ffe00000 (8190
> MB)
> > [ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4,
> Nodes=1
> > [ 0.000000] rcu: Hierarchical RCU implementation.
> > [ 0.000000] rcu: RCU restricting CPUs from NR_CPUS=8 to
> nr_cpu_ids=4.
> > [ 0.000000] rcu: RCU debug extended QS entry/exit.
> > [ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay is 25
> jiffies.
> > [ 0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16,
> nr_cpu_ids=4
> > [ 0.000000] NR_IRQS: 0, nr_irqs: 0, preallocated irqs: 0
> > [ 0.000000] plic: mapped 53 interrupts with 4 handlers for 9 contexts.
> > [ 0.000000] riscv_timer_init_dt: Registering clocksource cpuid [0] hartid
> [1]
> > [ 0.000000] clocksource: riscv_clocksource: mask: 0xffffffffffffffff
> max_cycles: 0x1d854df40, max_idle_ns: 3526361616960 ns
> > [ 0.000006] sched_clock: 64 bits at 1000kHz, resolution 1000ns, wraps
> every 2199023255500ns
> > [ 0.008564] Console: colour dummy device 80x25
> > [ 0.012994] Calibrating delay loop (skipped), value calculated using timer
> frequency.. 2.00 BogoMIPS (lpj=4000)
> > [ 0.023105] pid_max: default: 32768 minimum: 301
> > [ 0.028307] Mount-cache hash table entries: 16384 (order: 5, 131072
> bytes, linear)
> > [ 0.035768] Mountpoint-cache hash table entries: 16384 (order: 5,
> 131072 bytes, linear)
> > [ 0.045466] rcu: Hierarchical SRCU implementation.
> > [ 0.050232] smp: Bringing up secondary CPUs ...
> > [ 0.056183] smp: Brought up 1 node, 4 CPUs
> > [ 0.060951] devtmpfs: initialized
> > [ 0.065496] random: get_random_u32 called from
> bucket_table_alloc.isra.25+0x4e/0x160 with crng_init=0
> > [ 0.065883] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff,
> max_idle_ns: 7645041785100000 ns
> > [ 0.084236] futex hash table entries: 1024 (order: 4, 65536 bytes, linear)
> > [ 0.091933] NET: Registered protocol family 16
> > [ 0.112741] vgaarb: loaded
> > [ 0.115121] SCSI subsystem initialized
> > [ 0.119037] usbcore: registered new interface driver usbfs
> > [ 0.124200] usbcore: registered new interface driver hub
> > [ 0.129609] usbcore: registered new device driver usb
> > [ 0.135583] clocksource: Switched to clocksource riscv_clocksource
> > [ 0.149004] NET: Registered protocol family 2
> > [ 0.153401] tcp_listen_portaddr_hash hash table entries: 4096 (order: 5,
> 163840 bytes, linear)
> > [ 0.161940] TCP established hash table entries: 65536 (order: 7, 524288
> bytes, linear)
> > [ 0.171373] TCP bind hash table entries: 65536 (order: 9, 2097152 bytes,
> linear)
> > [ 0.185358] TCP: Hash tables configured (established 65536 bind 65536)
> > [ 0.191727] UDP hash table entries: 4096 (order: 6, 393216 bytes, linear)
> > [ 0.199402] UDP-Lite hash table entries: 4096 (order: 6, 393216 bytes,
> linear)
> > [ 0.207489] NET: Registered protocol family 1
> > [ 0.211848] RPC: Registered named UNIX socket transport module.
> > [ 0.217162] RPC: Registered udp transport module.
> > [ 0.221929] RPC: Registered tcp transport module.
> > [ 0.226704] RPC: Registered tcp NFSv4.1 backchannel transport module.
> > [ 0.233222] PCI: CLS 0 bytes, default 64
> > [ 0.585553] workingset: timestamp_bits=62 max_order=21
> bucket_order=0
> > [ 0.600753] NFS: Registering the id_resolver key type
> > [ 0.605171] Key type id_resolver registered
> > [ 0.609375] Key type id_legacy registered
> > [ 0.613468] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
> > [ 0.620391] 9p: Installing v9fs 9p2000 file system support
> > [ 0.626200] NET: Registered protocol family 38
> > [ 0.630359] Block layer SCSI generic (bsg) driver version 0.4 loaded
> (major 252)
> > [ 0.637773] io scheduler mq-deadline registered
> > [ 0.642371] io scheduler kyber registered
> > [ 0.707353] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
> > [ 0.714231] 10010000.serial: ttySIF0 at MMIO 0x10010000 (irq = 1,
> base_baud = 0) is a SiFive UART v0
> > [ 0.722691] BUG: spinlock bad magic on CPU#3, swapper/0/1
> > [ 0.728140] lock: 0xffffffe1f63ae018, .magic: 00000000, .owner: <none>/-
> 1, .owner_cpu: 0
> > [ 0.736388] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.7.0-rc4-00001-
> g0319a09-dirty #2
> > [ 0.744456] Call Trace:
> > [ 0.746983] [<ffffffe0006024c6>] walk_stackframe+0x0/0xa4
> > [ 0.752448] [<ffffffe0006026ac>] show_stack+0x2a/0x34
> > [ 0.757577] [<ffffffe000869f68>] dump_stack+0x6a/0x84
> > [ 0.762701] [<ffffffe000643060>] spin_dump+0x68/0x74
> > [ 0.767730] [<ffffffe000642c80>] do_raw_spin_lock+0xb0/0xcc
> > [ 0.773379] [<ffffffe000c3f528>] _raw_spin_lock_irqsave+0x20/0x2c
> > [ 0.779538] [<ffffffe0008d9aec>] uart_add_one_port+0x2f6/0x406
> > [ 0.785441] [<ffffffe0008e3974>] sifive_serial_probe+0x184/0x270
> > [ 0.791527] [<ffffffe000a1323c>] platform_drv_probe+0x32/0x5e
> > [ 0.797335] [<ffffffe000a11a2e>] really_probe+0x9a/0x21e
> > [ 0.802719] [<ffffffe000a11cb4>] driver_probe_device+0x2e/0x88
> > [ 0.808623] [<ffffffe000a11e86>] device_driver_attach+0x4c/0x50
> > [ 0.814613] [<ffffffe000a11ec4>] __driver_attach+0x3a/0xac
> > [ 0.820170] [<ffffffe000a1002a>] bus_for_each_dev+0x4a/0x72
> > [ 0.825813] [<ffffffe000a1153a>] driver_attach+0x1a/0x22
> > [ 0.831196] [<ffffffe000a1106c>] bus_add_driver+0x192/0x198
> > [ 0.836840] [<ffffffe000a123b2>] driver_register+0x3a/0xd0
> > [ 0.842397] [<ffffffe000a13202>] __platform_driver_register+0x3a/0x42
> > [ 0.848911] [<ffffffe00001749c>] sifive_serial_init+0x30/0x50
> > [ 0.854730] [<ffffffe0006000d0>] do_one_initcall+0x50/0x15a
> > [ 0.860369] [<ffffffe000001c80>] kernel_init_freeable+0x16a/0x1de
> > [ 0.866533] [<ffffffe000c3ad3c>] kernel_init+0x12/0x118
> > [ 0.871830] [<ffffffe00060120a>] ret_from_exception+0x0/0xc
> > [ 0.877524] printk: console [ttySIF0] enabled
> > [ 0.877524] printk: console [ttySIF0] enabled
> > [ 0.886258] printk: bootconsole [sbi0] disabled
> > [ 0.886258] printk: bootconsole [sbi0] disabled
> >
> > The kernel doesn't hang and boots to prompt.
> >
> >
> ===============================================================
> >
> > Adding the missing spin_lock_init fixes the spinlock error. With the
> > patch the serial port is tested with basic sanity checks of baudrate
> > change, receive and transmit using:
> >
> > Change baud rate : stty -F /dev/ttySIF0 9600
> > Recive mode : cat /dev/ttySIF0
> > Transmit mode : echo "Hello" > /dev/ttySIF0
> >
> > Some of the relevant boot log:
> > =================================
> > [ 0.642457] io scheduler kyber registered
> > [ 0.704650] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
> > [ 0.711531] 10010000.serial: ttySIF0 at MMIO 0x10010000 (irq = 1,
> base_baud = 0) is a SiFive UART v0
> > [ 0.720013] printk: console [ttySIF0] enabled
> > [ 0.720013] printk: console [ttySIF0] enabled
> > [ 0.728755] printk: bootconsole [sbi0] disabled
> > [ 0.728755] printk: bootconsole [sbi0] disabled
> > [ 0.738182] 10011000.serial: ttySIF1 at MMIO 0x10011000 (irq = 10,
> base_baud = 0) is a SiFive UART v0
> > [ 0.747674] [drm] radeon kernel modesetting enabled.
> > [ 0.766381] loop: module loaded
> >
> >
> > Sagar Shrikant Kadam (1):
> > tty: serial: add missing spin_lock_init for SiFive UART
> >
> > drivers/tty/serial/sifive.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > --
> > 2.7.4
> >
> >
> Just for future reference:
> This should be sent as a part of the series (PATCH 0/1) as this is a cover
> letter for the series.
>
Thanks for mentioning this.
Yes, I will make a note of it for future and have appropriate sequence for
cover letter's
BR,
Sagar Kadam
> --
> Regards,
> Atish
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] tty: serial: add missing spin_lock_init for SiFive UART
2020-05-06 19:26 ` [PATCH] tty: serial: add missing spin_lock_init for " Sagar Shrikant Kadam
2020-05-06 23:10 ` Atish Patra
@ 2020-05-07 6:49 ` Greg KH
2020-05-07 17:32 ` Palmer Dabbelt
1 sibling, 1 reply; 9+ messages in thread
From: Greg KH @ 2020-05-07 6:49 UTC (permalink / raw
To: Sagar Shrikant Kadam
Cc: Atish.Patra, linux-riscv, Anup.Patel, palmer, paul.walmsley
On Wed, May 06, 2020 at 12:26:52PM -0700, Sagar Shrikant Kadam wrote:
> Uninitialised spin lock on sifive serial port (ssp) raised
> a race condition and resulted in spin lock bad magic as
> reported and discussed here [1]
> Initialising the spin lock resolves the issue.
>
> The fix is tested on HiFive Unleashed A00 board with Linux 5.7-rc4
> and OpenSBI v0.7
>
> [1] http://lists.infradead.org/pipermail/linux-riscv/2020-May/009713.html
In the future, can you link to lore.kernel.org instead?
>
> Fixes: 45c054d0815b ("tty: serial: add driver for the SiFive UART")
So this should also go to stable kernels, right?
> Reported-by: Atish Patra <Atish.Patra@wdc.com>
> Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
> ---
> drivers/tty/serial/sifive.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
> index 13eadcb..b061bdb 100644
> --- a/drivers/tty/serial/sifive.c
> +++ b/drivers/tty/serial/sifive.c
> @@ -989,6 +989,7 @@ static int sifive_serial_probe(struct platform_device *pdev)
> ssp->clk = clk;
> ssp->clk_notifier.notifier_call = sifive_serial_clk_notifier;
>
> + spin_lock_init(&ssp->port.lock);
Shouldn't the port lock be initialized by the tty core instead? I think
this is the second time I've seen this type of fix needed recently...
thanks,
greg k-h
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH] tty: serial: add missing spin_lock_init for SiFive UART
2020-05-07 6:49 ` Greg KH
@ 2020-05-07 17:32 ` Palmer Dabbelt
2020-05-08 7:16 ` Sagar Kadam
0 siblings, 1 reply; 9+ messages in thread
From: Palmer Dabbelt @ 2020-05-07 17:32 UTC (permalink / raw
To: Greg KH; +Cc: Atish Patra, linux-riscv, Anup Patel, sagar.kadam, Paul Walmsley
On Wed, 06 May 2020 23:49:58 PDT (-0700), Greg KH wrote:
> On Wed, May 06, 2020 at 12:26:52PM -0700, Sagar Shrikant Kadam wrote:
>> Uninitialised spin lock on sifive serial port (ssp) raised
>> a race condition and resulted in spin lock bad magic as
>> reported and discussed here [1]
>> Initialising the spin lock resolves the issue.
>>
>> The fix is tested on HiFive Unleashed A00 board with Linux 5.7-rc4
>> and OpenSBI v0.7
>>
>> [1] http://lists.infradead.org/pipermail/linux-riscv/2020-May/009713.html
>
> In the future, can you link to lore.kernel.org instead?
>
>>
>> Fixes: 45c054d0815b ("tty: serial: add driver for the SiFive UART")
>
> So this should also go to stable kernels, right?
>
>> Reported-by: Atish Patra <Atish.Patra@wdc.com>
>> Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
>> ---
>> drivers/tty/serial/sifive.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
>> index 13eadcb..b061bdb 100644
>> --- a/drivers/tty/serial/sifive.c
>> +++ b/drivers/tty/serial/sifive.c
>> @@ -989,6 +989,7 @@ static int sifive_serial_probe(struct platform_device *pdev)
>> ssp->clk = clk;
>> ssp->clk_notifier.notifier_call = sifive_serial_clk_notifier;
>>
>> + spin_lock_init(&ssp->port.lock);
>
> Shouldn't the port lock be initialized by the tty core instead? I think
> this is the second time I've seen this type of fix needed recently...
Ya, that's what was blocking my reviewed-by. It looks like the spinlock isn't
initialized for console. IDK why that's the case, but assuming that's the way
it's supposed to work we should only initialize the spinlock if we set up a
console port, which we do in __ssp_add_console_port(). In other words,
something like this
diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c
index 13eadcb8aec4..0b5110dad051 100644
--- a/drivers/tty/serial/sifive.c
+++ b/drivers/tty/serial/sifive.c
@@ -883,6 +883,7 @@ console_initcall(sifive_console_init);
static void __ssp_add_console_port(struct sifive_serial_port *ssp)
{
+ spin_lock_init(&ssp->port.lock);
sifive_serial_console_ports[ssp->port.line] = ssp;
}
>
> thanks,
>
> greg k-h
^ permalink raw reply related [flat|nested] 9+ messages in thread
* RE: [PATCH] tty: serial: add missing spin_lock_init for SiFive UART
2020-05-07 17:32 ` Palmer Dabbelt
@ 2020-05-08 7:16 ` Sagar Kadam
0 siblings, 0 replies; 9+ messages in thread
From: Sagar Kadam @ 2020-05-08 7:16 UTC (permalink / raw
To: Palmer Dabbelt, Greg KH
Cc: Atish Patra, linux-riscv@lists.infradead.org, Anup Patel,
Paul Walmsley
Hello,
> -----Original Message-----
> From: Palmer Dabbelt <palmer@dabbelt.com>
> Sent: Thursday, May 7, 2020 11:03 PM
> To: Greg KH <gregkh@linuxfoundation.org>
> Cc: Sagar Kadam <sagar.kadam@sifive.com>; Paul Walmsley
> <paul.walmsley@sifive.com>; linux-riscv@lists.infradead.org; Atish Patra
> <Atish.Patra@wdc.com>; Anup Patel <Anup.Patel@wdc.com>
> Subject: Re: [PATCH] tty: serial: add missing spin_lock_init for SiFive UART
>
> [External Email] Do not click links or attachments unless you recognize the
> sender and know the content is safe
>
> On Wed, 06 May 2020 23:49:58 PDT (-0700), Greg KH wrote:
> > On Wed, May 06, 2020 at 12:26:52PM -0700, Sagar Shrikant Kadam wrote:
> >> Uninitialised spin lock on sifive serial port (ssp) raised a race
> >> condition and resulted in spin lock bad magic as reported and
> >> discussed here [1] Initialising the spin lock resolves the issue.
> >>
> >> The fix is tested on HiFive Unleashed A00 board with Linux 5.7-rc4
> >> and OpenSBI v0.7
> >>
> >> [1]
> >> http://lists.infradead.org/pipermail/linux-riscv/2020-May/009713.html
> >
> > In the future, can you link to lore.kernel.org instead?
> >
Thanks for suggestions, Greg.
Yes, will update link from lore.kernel.org
> >>
> >> Fixes: 45c054d0815b ("tty: serial: add driver for the SiFive UART")
> >
> > So this should also go to stable kernels, right?
> >
Yes, I will include linux-kernel and linux-serial as well in V2
> >> Reported-by: Atish Patra <Atish.Patra@wdc.com>
> >> Signed-off-by: Sagar Shrikant Kadam <sagar.kadam@sifive.com>
> >> ---
> >> drivers/tty/serial/sifive.c | 1 +
> >> 1 file changed, 1 insertion(+)
> >>
> >> diff --git a/drivers/tty/serial/sifive.c
> >> b/drivers/tty/serial/sifive.c index 13eadcb..b061bdb 100644
> >> --- a/drivers/tty/serial/sifive.c
> >> +++ b/drivers/tty/serial/sifive.c
> >> @@ -989,6 +989,7 @@ static int sifive_serial_probe(struct
> platform_device *pdev)
> >> ssp->clk = clk;
> >> ssp->clk_notifier.notifier_call = sifive_serial_clk_notifier;
> >>
> >> + spin_lock_init(&ssp->port.lock);
> >
> > Shouldn't the port lock be initialized by the tty core instead? I
> > think this is the second time I've seen this type of fix needed recently...
>
> Ya, that's what was blocking my reviewed-by. It looks like the spinlock isn't
> initialized for console. IDK why that's the case, but assuming that's the way
> it's supposed to work we should only initialize the spinlock if we set up a
> console port, which we do in __ssp_add_console_port(). In other words,
> something like this
>
Thanks Greg and Palmer, your inputs are valuable. I could see that the tty core does
initialise the port spin lock via tty_port_init while registering the uart_driver, while
there isn't any lock initialized for console. The serial_core ensure the spin lock for
console is initialised (uart_port_spin_lock_init) and since it is missing in our case we
encounter the spin_lock error.
I have verified that spin_lock init for ssp console works, and will submit a v2.
Thanks & BR,
Sagar Kadam
> diff --git a/drivers/tty/serial/sifive.c b/drivers/tty/serial/sifive.c index
> 13eadcb8aec4..0b5110dad051 100644
> --- a/drivers/tty/serial/sifive.c
> +++ b/drivers/tty/serial/sifive.c
> @@ -883,6 +883,7 @@ console_initcall(sifive_console_init);
>
> static void __ssp_add_console_port(struct sifive_serial_port *ssp) {
> + spin_lock_init(&ssp->port.lock);
> sifive_serial_console_ports[ssp->port.line] = ssp; }
>
> >
> > thanks,
> >
> > greg k-h
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2020-05-08 7:17 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-05-06 19:26 [PATCH] fix for spin lock bad magic on SiFive UART Sagar Shrikant Kadam
2020-05-06 19:26 ` [PATCH] tty: serial: add missing spin_lock_init for " Sagar Shrikant Kadam
2020-05-06 23:10 ` Atish Patra
2020-05-07 3:34 ` Sagar Kadam
2020-05-07 6:49 ` Greg KH
2020-05-07 17:32 ` Palmer Dabbelt
2020-05-08 7:16 ` Sagar Kadam
2020-05-06 23:12 ` [PATCH] fix for spin lock bad magic on " Atish Patra
2020-05-07 3:59 ` Sagar Kadam
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