From: Yujie Liu <yujie.liu@intel.com>
To: "Paul E. McKenney" <paulmck@kernel.org>,
Geert Uytterhoeven <geert@linux-m68k.org>
Cc: <linux-arch@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<elver@google.com>, <akpm@linux-foundation.org>,
<tglx@linutronix.de>, <peterz@infradead.org>,
<dianders@chromium.org>, <pmladek@suse.com>,
<torvalds@linux-foundation.org>, Arnd Bergmann <arnd@arndb.de>,
Andi Shyti <andi.shyti@linux.intel.com>
Subject: Re: [PATCH cmpxchg 13/14] xtensa: Emulate one-byte cmpxchg
Date: Fri, 19 Apr 2024 13:07:44 +0800 [thread overview]
Message-ID: <ZiH8IBiLkYw7M281@yujie-X299> (raw)
In-Reply-To: <620a10e8-f5c0-4e23-8403-492ab1c7f110@paulmck-laptop>
On Thu, Apr 18, 2024 at 04:21:46PM -0700, Paul E. McKenney wrote:
> On Thu, Apr 18, 2024 at 10:06:21AM +0200, Geert Uytterhoeven wrote:
> > Hi Paul,
> >
> > On Mon, Apr 8, 2024 at 7:49 PM Paul E. McKenney <paulmck@kernel.org> wrote:
> > > Use the new cmpxchg_emu_u8() to emulate one-byte cmpxchg() on xtensa.
> > >
> > > [ paulmck: Apply kernel test robot feedback. ]
> > > [ paulmck: Drop two-byte support per Arnd Bergmann feedback. ]
> > >
> > > Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
> >
> > Thanks for your patch!
> >
> > > --- a/arch/xtensa/include/asm/cmpxchg.h
> > > +++ b/arch/xtensa/include/asm/cmpxchg.h
> > > @@ -74,6 +75,7 @@ static __inline__ unsigned long
> > > __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
> > > {
> > > switch (size) {
> > > + case 1: return cmpxchg_emu_u8((volatile u8 *)ptr, old, new);
> >
> > The cast is not needed.
>
> In both cases, kernel test robot yelled at me when it was not present.
>
> Happy to resubmit without it, though, if that is a yell that I should
> have ignored.
FYI, kernel test robot did yell some reports on various architectures such as:
[1] https://lore.kernel.org/oe-kbuild-all/202403292321.T55etywH-lkp@intel.com/
[2] https://lore.kernel.org/oe-kbuild-all/202404040526.GVzaL2io-lkp@intel.com/
[3] https://lore.kernel.org/oe-kbuild-all/202404022106.mYwpypit-lkp@intel.com/
In brief, there were mainly three types of issues:
* The cmpxchg-emu.h header is missing
* The parameters of cmpxchg_emu_u8 need to be cast to corresponding types
* The return value of cmpxchg_emu_u8 needs to be cast to the "ret" type
As for this specific case of xtensa arch, the compiler doesn't warn
regardless of whether there is an explicit cast for "ptr" or not.
The "ptr" being passed in is "void *", and it seems that a "void *"
pointer can be automatically cast to any other type of pointer, so it
is not necessary to have an explicit cast of "u8 *".
As for the implementations of other architectures that don't pass the
"ptr" as "void *" (such as a macro implementation), the explicit cast to
"u8 *" may still be required.
Thanks,
Yujie
>
> Thanx, Paul
>
> > > case 4: return __cmpxchg_u32(ptr, old, new);
> > > default: __cmpxchg_called_with_bad_pointer();
> > > return old;
> >
> > Gr{oetje,eeting}s,
> >
> > Geert
> >
> > --
> > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> >
> > In personal conversations with technical people, I call myself a hacker. But
> > when I'm talking to journalists I just say "programmer" or something like that.
> > -- Linus Torvalds
next prev parent reply other threads:[~2024-04-19 5:14 UTC|newest]
Thread overview: 125+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-01 21:39 [PATCH RFC cmpxchg 0/8] Provide emulation for one- and two-byte cmpxchg() Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 1/8] lib: Add one-byte and two-byte cmpxchg() emulation functions Paul E. McKenney
2024-04-02 13:07 ` Marco Elver
2024-04-02 17:15 ` Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 2/8] sparc: Emulate one-byte and two-byte cmpxchg Paul E. McKenney
2024-04-01 22:38 ` Al Viro
2024-04-01 23:58 ` Paul E. McKenney
2024-04-02 0:07 ` Al Viro
2024-04-02 3:37 ` Al Viro
2024-04-02 4:11 ` Al Viro
2024-04-02 4:18 ` Paul E. McKenney
2024-04-02 4:28 ` [PATCH 1/8] sparc32: make __cmpxchg_u32() return u32 Al Viro
2024-04-02 4:28 ` [PATCH 2/8] sparc32: make the first argument of __cmpxchg_u64() volatile u64 * Al Viro
2024-04-02 4:28 ` [PATCH 3/8] sparc32: unify __cmpxchg_u{32,64} Al Viro
2024-04-02 7:28 ` Arnd Bergmann
2024-04-02 20:02 ` Paul E. McKenney
2024-04-02 4:28 ` [PATCH 4/8] sparc32: add __cmpxchg_u{8,16}() and teach __cmpxchg() to handle those sizes Al Viro
2024-04-02 4:28 ` [PATCH 5/8] parisc: __cmpxchg_u32(): lift conversion into the callers Al Viro
2024-04-02 4:28 ` [PATCH 6/8] parisc: unify implementations of __cmpxchg_u{8,32,64} Al Viro
2024-04-02 4:28 ` [PATCH 7/8] parisc: add missing export of __cmpxchg_u8() Al Viro
2024-04-02 4:28 ` [PATCH 8/8] parisc: add u16 support to cmpxchg() Al Viro
2024-04-02 20:03 ` [PATCH 1/8] sparc32: make __cmpxchg_u32() return u32 Paul E. McKenney
2024-04-03 22:20 ` Al Viro
2024-04-04 3:09 ` Paul E. McKenney
2024-04-02 4:17 ` [PATCH RFC cmpxchg 2/8] sparc: Emulate one-byte and two-byte cmpxchg Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 3/8] ARC: " Paul E. McKenney
2024-04-02 8:14 ` Arnd Bergmann
2024-04-02 17:06 ` Paul E. McKenney
2024-04-02 20:52 ` Paul E. McKenney
2024-04-04 11:57 ` Arnd Bergmann
2024-04-04 14:44 ` Paul E. McKenney
2024-04-04 15:06 ` Arnd Bergmann
2024-04-01 21:39 ` [PATCH RFC cmpxchg 4/8] csky: " Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 5/8] sh: " Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 6/8] xtensa: " Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 7/8] parisc: Emulate " Paul E. McKenney
2024-04-01 21:39 ` [PATCH RFC cmpxchg 8/8] riscv: Emulate one-byte and " Paul E. McKenney
2024-04-04 14:15 ` Palmer Dabbelt
2024-04-04 14:50 ` Paul E. McKenney
2024-05-11 6:50 ` Guo Ren
2024-05-11 14:54 ` Paul E. McKenney
2024-05-11 20:44 ` Leonardo Bras
2024-04-08 17:47 ` [PATCH RFC cmpxchg 0/8] Provide emulation for one- and two-byte cmpxchg() Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 01/14] sparc32: make __cmpxchg_u32() return u32 Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 02/14] sparc32: make the first argument of __cmpxchg_u64() volatile u64 * Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 03/14] sparc32: unify __cmpxchg_u{32,64} Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 04/14] sparc32: add __cmpxchg_u{8,16}() and teach __cmpxchg() to handle those sizes Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 05/14] parisc: __cmpxchg_u32(): lift conversion into the callers Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 06/14] parisc: unify implementations of __cmpxchg_u{8,32,64} Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 07/14] parisc: add missing export of __cmpxchg_u8() Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 08/14] parisc: add u16 support to cmpxchg() Paul E. McKenney
2024-04-08 20:10 ` Linus Torvalds
2024-04-08 20:53 ` Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 09/14] lib: Add one-byte emulation function Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 10/14] ARC: Emulate one-byte cmpxchg Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 11/14] csky: " Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 12/14] sh: " Paul E. McKenney
2024-04-18 8:04 ` Geert Uytterhoeven
2024-04-08 17:49 ` [PATCH cmpxchg 13/14] xtensa: " Paul E. McKenney
2024-04-18 8:06 ` Geert Uytterhoeven
2024-04-18 23:21 ` Paul E. McKenney
2024-04-19 5:07 ` Yujie Liu [this message]
2024-04-19 8:02 ` Geert Uytterhoeven
2024-04-20 14:03 ` Paul E. McKenney
2024-04-08 17:49 ` [PATCH cmpxchg 14/14] riscv: " Paul E. McKenney
2024-04-09 17:35 ` Andrea Parri
2024-04-09 18:08 ` Paul E. McKenney
2024-05-01 22:58 ` [PATCH v2 cmpxchg 0/8] Provide emulation for one--byte cmpxchg() Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 01/13] sparc32: make __cmpxchg_u32() return u32 Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 02/13] sparc32: make the first argument of __cmpxchg_u64() volatile u64 * Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 03/13] sparc32: unify __cmpxchg_u{32,64} Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 04/13] sparc32: add __cmpxchg_u{8,16}() and teach __cmpxchg() to handle those sizes Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 05/13] parisc: __cmpxchg_u32(): lift conversion into the callers Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 06/13] parisc: unify implementations of __cmpxchg_u{8,32,64} Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 07/13] parisc: add missing export of __cmpxchg_u8() Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 08/13] parisc: add u16 support to cmpxchg() Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 09/13] lib: Add one-byte emulation function Paul E. McKenney
2024-05-13 14:44 ` Boqun Feng
2024-05-13 15:41 ` Paul E. McKenney
2024-05-13 15:57 ` Boqun Feng
2024-05-13 21:19 ` Boqun Feng
2024-05-14 14:22 ` Paul E. McKenney
2024-05-14 14:53 ` Boqun Feng
2024-05-14 15:02 ` Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 10/13] ARC: Emulate one-byte cmpxchg Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 11/13] csky: " Paul E. McKenney
2024-05-11 6:42 ` Guo Ren
2024-05-11 14:49 ` Paul E. McKenney
2024-05-01 23:01 ` [PATCH v2 cmpxchg 12/13] sh: " Paul E. McKenney
2024-05-02 4:52 ` John Paul Adrian Glaubitz
2024-05-02 5:06 ` Paul E. McKenney
2024-05-02 5:11 ` John Paul Adrian Glaubitz
2024-05-02 13:33 ` Paul E. McKenney
2024-05-02 20:53 ` Al Viro
2024-05-02 21:01 ` alpha cmpxchg.h (was Re: [PATCH v2 cmpxchg 12/13] sh: Emulate one-byte cmpxchg) Al Viro
2024-05-02 22:16 ` Linus Torvalds
2024-05-02 21:18 ` [PATCH v2 cmpxchg 12/13] sh: Emulate one-byte cmpxchg Paul E. McKenney
2024-05-02 22:07 ` Al Viro
2024-05-02 23:12 ` Paul E. McKenney
2024-05-02 23:24 ` Al Viro
2024-05-02 23:45 ` Paul E. McKenney
2024-05-02 23:32 ` Linus Torvalds
2024-05-03 0:16 ` Paul E. McKenney
2024-05-02 21:50 ` Arnd Bergmann
2024-05-02 5:42 ` D. Jeff Dionne
2024-05-02 11:30 ` Arnd Bergmann
2024-05-01 23:01 ` [PATCH v2 cmpxchg 13/13] xtensa: " Paul E. McKenney
2024-05-02 20:01 ` [PATCH v2 cmpxchg 0/8] Provide emulation for one--byte cmpxchg() Al Viro
2024-05-02 21:20 ` Paul E. McKenney
2024-06-04 17:02 ` [PATCH v3 cmpxchg 0/4] " Paul E. McKenney
2024-06-04 17:04 ` [PATCH v3 cmpxchg 1/4] ARC: Emulate one-byte cmpxchg Paul E. McKenney
2024-06-04 17:04 ` [PATCH v3 cmpxchg 2/4] sh: " Paul E. McKenney
2024-06-04 17:09 ` John Paul Adrian Glaubitz
2024-06-04 17:50 ` Paul E. McKenney
2024-06-04 17:56 ` John Paul Adrian Glaubitz
2024-06-04 21:14 ` Paul E. McKenney
2024-06-17 16:50 ` Paul E. McKenney
2024-06-17 20:30 ` John Paul Adrian Glaubitz
2024-06-17 21:59 ` Paul E. McKenney
2024-06-04 17:04 ` [PATCH v3 cmpxchg 3/4] xtensa: " Paul E. McKenney
2024-06-04 17:04 ` [PATCH v3 cmpxchg 4/4] ARM: " Paul E. McKenney
2024-06-04 20:52 ` Linus Walleij
2024-06-04 21:14 ` Paul E. McKenney
2024-06-05 8:38 ` Linus Walleij
2024-06-05 18:05 ` Paul E. McKenney
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