From: andre.przywara@arm.com (Andre Przywara) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH] serial/amba-pl011: Disable interrupts around TX softirq Date: Mon, 15 Jun 2015 12:09:59 +0100 [thread overview] Message-ID: <557EB287.300@arm.com> (raw) In-Reply-To: <20150613003945.GA10941@kroah.com> Hi Greg, On 06/13/2015 01:39 AM, Greg Kroah-Hartman wrote: > On Fri, Jun 05, 2015 at 03:07:47PM +0100, Dave Martin wrote: >> pl011_tx_softirq() currently uses spin_{,un}lock(), which are not >> sufficient to inhibit pl011_int() from being triggered by a local >> IRQ and trying to re-take the same lock. This can lead to >> deadlocks. >> >> This patch uses the _irq() locking variants instead to ensure that >> pl011_int() handling for a given port is deferred until any >> pl011_tx_softirq() work for that port is complete. >> >> Signed-off-by: Dave Martin <Dave.Martin@arm.com> >> Tested-by: Robin Murphy <robin.murphy@arm.com> >> Cc: stable <stable@vger.kernel.org> # 4.1 >> --- >> >> Another candidate for v4.1 if possible (sorry!) -- I thought this change >> was already in, but it went astray when I was refactoring. > > Too late for 4.1, sorry. So if I get this correctly, we go from "some characters lost from systemd messages" behaviour in 4.0 to "may deadlock" in 4.1 now? Is that right? I understand that you are reluctant to take this patch this late in the game, but wouldn't it actually be better now to revert PL011 to the state of 4.0 to avoid ending up with worse-than-4.0 behaviour in the 4.1 release? We could still backport the solution ending up in 4.2-rc to 4.1.x. Cheers, Andre. > This doesn't apply to my tty-next branch, > otherwise I would have queued it up there. Care to redo it and mark it > for -stable, like I did above, and resend it? > > thanks, > > greg k-h >
WARNING: multiple messages have this Message-ID (diff)
From: Andre Przywara <andre.przywara@arm.com> To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Dave P Martin <Dave.Martin@arm.com> Cc: "Russell King" <linux@arm.linux.org.uk>, "Jakub Kiciński" <moorray3@wp.pl>, "Andrew Jackson" <Andrew.Jackson@arm.com>, "Graeme Gregory" <gg@slimlogic.co.uk>, "linux-serial@vger.kernel.org" <linux-serial@vger.kernel.org>, "popcorn mix" <popcornmix@gmail.com>, "Jorge Ramirez-Ortiz" <jorge.ramirez-ortiz@linaro.org>, "Robin Murphy" <Robin.Murphy@arm.com>, "linux-arm-kernel@lists.infradead.org" <linux-arm-kernel@lists.infradead.org> Subject: Re: [PATCH] serial/amba-pl011: Disable interrupts around TX softirq Date: Mon, 15 Jun 2015 12:09:59 +0100 [thread overview] Message-ID: <557EB287.300@arm.com> (raw) In-Reply-To: <20150613003945.GA10941@kroah.com> Hi Greg, On 06/13/2015 01:39 AM, Greg Kroah-Hartman wrote: > On Fri, Jun 05, 2015 at 03:07:47PM +0100, Dave Martin wrote: >> pl011_tx_softirq() currently uses spin_{,un}lock(), which are not >> sufficient to inhibit pl011_int() from being triggered by a local >> IRQ and trying to re-take the same lock. This can lead to >> deadlocks. >> >> This patch uses the _irq() locking variants instead to ensure that >> pl011_int() handling for a given port is deferred until any >> pl011_tx_softirq() work for that port is complete. >> >> Signed-off-by: Dave Martin <Dave.Martin@arm.com> >> Tested-by: Robin Murphy <robin.murphy@arm.com> >> Cc: stable <stable@vger.kernel.org> # 4.1 >> --- >> >> Another candidate for v4.1 if possible (sorry!) -- I thought this change >> was already in, but it went astray when I was refactoring. > > Too late for 4.1, sorry. So if I get this correctly, we go from "some characters lost from systemd messages" behaviour in 4.0 to "may deadlock" in 4.1 now? Is that right? I understand that you are reluctant to take this patch this late in the game, but wouldn't it actually be better now to revert PL011 to the state of 4.0 to avoid ending up with worse-than-4.0 behaviour in the 4.1 release? We could still backport the solution ending up in 4.2-rc to 4.1.x. Cheers, Andre. > This doesn't apply to my tty-next branch, > otherwise I would have queued it up there. Care to redo it and mark it > for -stable, like I did above, and resend it? > > thanks, > > greg k-h >
next prev parent reply other threads:[~2015-06-15 11:09 UTC|newest] Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-06-05 14:07 [PATCH] serial/amba-pl011: Disable interrupts around TX softirq Dave Martin 2015-06-05 14:07 ` Dave Martin 2015-06-05 18:03 ` Robin Murphy 2015-06-05 18:03 ` Robin Murphy 2015-06-08 10:34 ` Robin Murphy 2015-06-08 10:34 ` Robin Murphy 2015-06-08 11:34 ` Dave P Martin 2015-06-08 11:34 ` Dave P Martin 2015-06-13 0:39 ` Greg Kroah-Hartman 2015-06-13 0:39 ` Greg Kroah-Hartman 2015-06-15 10:53 ` Dave P Martin 2015-06-15 10:53 ` Dave P Martin 2015-06-15 11:09 ` Andre Przywara [this message] 2015-06-15 11:09 ` Andre Przywara 2015-06-15 14:03 ` Dave Martin 2015-06-15 14:03 ` Dave Martin -- strict thread matches above, loose matches on Subject: below -- 2015-06-18 13:54 Dave Martin 2015-06-18 13:54 ` Dave Martin 2015-06-20 9:09 ` Stefan Wahren 2015-06-20 9:09 ` Stefan Wahren 2015-06-20 9:09 ` Stefan Wahren 2015-06-23 11:13 ` Dave P Martin 2015-06-23 11:13 ` Dave P Martin 2015-07-09 10:57 Dave Martin 2015-07-09 10:57 ` Dave Martin 2015-07-23 22:05 ` Greg Kroah-Hartman 2015-07-23 22:05 ` Greg Kroah-Hartman 2015-07-24 9:56 ` Dave Martin 2015-07-24 9:56 ` Dave Martin 2015-07-24 15:15 ` Greg Kroah-Hartman 2015-07-24 15:15 ` Greg Kroah-Hartman 2015-07-24 16:46 ` Dave Martin 2015-07-24 16:46 ` Dave Martin
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