From: Michal Hocko <mhocko@kernel.org> To: Ingo Molnar <mingo@kernel.org> Cc: LKML <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>, "David S. Miller" <davem@davemloft.net>, Tony Luck <tony.luck@intel.com>, Andrew Morton <akpm@linux-foundation.org>, Chris Zankel <chris@zankel.net>, Max Filippov <jcmvbkbc@gmail.com>, x86@kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org, Josh Poimboeuf <jpoimboe@redhat.com> Subject: Re: [PATCH 10/11] x86, rwsem: provide __down_write_killable Date: Sun, 17 Apr 2016 12:59:21 -0400 [thread overview] Message-ID: <20160417165920.GA9051@dhcp22.suse.cz> (raw) In-Reply-To: <20160413124943.GH14351@dhcp22.suse.cz> On Wed 13-04-16 14:49:43, Michal Hocko wrote: > On Wed 13-04-16 12:27:31, Ingo Molnar wrote: > > > > * Ingo Molnar <mingo@kernel.org> wrote: > > > > > I'm testing your patches today, if they are otherwise OK [...] > > > > got this build failure: > > > > ./arch/x86/include/asm/rwsem.h:106:2: error: ‘asm’ operand has impossible constraints > > Hmm, I have no idea why 64b didn't have problem with the asm but 32b > complains. Anyway, the following makes both happy. I have checked the > generated code for 64b and it hasn't changed after the patch. 32b also > seems to be generating a proper code. My gcc asm()-foo is rather weak so > I would feel better if somebody double checked after me. Peter, Ingo, does the patch makes sense to you? Thanks! > --- > From d23f4e6994670bf2c5d864f2190f21022b4499b2 Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@suse.com> > Date: Wed, 13 Apr 2016 14:21:25 +0200 > Subject: [PATCH] x86: __down_read_trylock fix 32b build failure > MIME-Version: 1.0 > Content-Type: text/plain; charset=UTF-8 > Content-Transfer-Encoding: 8bit > > Ingo has noticed the following compilation error with CONFIG_X86_32=y > ./arch/x86/include/asm/rwsem.h:106:2: error: ‘asm’ operand has impossible constraints > > The reason seems to be that 32b doesn't like ret being input and output > argument sharing the same register with sem which is only the input. Fix > this by making ret output only and use %3 (aka sem) for xadd. > > ret initialization is not needed now because this is done implicitly > by the asm even for the fast path as both sem and ret share the same > register. > > Reported-by: Ingo Molnar <mingo@kernel.org> > Signed-off-by: Michal Hocko <mhocko@suse.com> > --- > arch/x86/include/asm/rwsem.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h > index d759c5f70f49..453744c1d347 100644 > --- a/arch/x86/include/asm/rwsem.h > +++ b/arch/x86/include/asm/rwsem.h > @@ -102,9 +102,9 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) > #define ____down_write(sem, slow_path) \ > ({ \ > long tmp; \ > - struct rw_semaphore* ret = sem; \ > + struct rw_semaphore* ret; \ > asm volatile("# beginning down_write\n\t" \ > - LOCK_PREFIX " xadd %1,(%2)\n\t" \ > + LOCK_PREFIX " xadd %1,(%3)\n\t" \ > /* adds 0xffff0001, returns the old value */ \ > " test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" \ > /* was the active mask 0 before? */\ > @@ -112,7 +112,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) > " call " slow_path "\n" \ > "1:\n" \ > "# ending down_write" \ > - : "+m" (sem->count), "=d" (tmp), "+a" (ret) \ > + : "+m" (sem->count), "=d" (tmp), "=a" (ret) \ > : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS) \ > : "memory", "cc"); \ > ret; \ > -- > 2.8.0.rc3 > > -- > Michal Hocko > SUSE Labs -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-alpha" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: Ingo Molnar <mingo@kernel.org> Cc: LKML <linux-kernel@vger.kernel.org>, Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>, "H. Peter Anvin" <hpa@zytor.com>, "David S. Miller" <davem@davemloft.net>, Tony Luck <tony.luck@intel.com>, Andrew Morton <akpm@linux-foundation.org>, Chris Zankel <chris@zankel.net>, Max Filippov <jcmvbkbc@gmail.com>, x86@kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-xtensa@linux-xtensa.org, linux-arch@vger.kernel.org, Josh Poimboeuf <jpoimboe@redhat.com> Subject: Re: [PATCH 10/11] x86, rwsem: provide __down_write_killable Date: Sun, 17 Apr 2016 12:59:21 -0400 [thread overview] Message-ID: <20160417165920.GA9051@dhcp22.suse.cz> (raw) Message-ID: <20160417165921.lUH6RCvlmEK57mpNVUjrv1_U6k6Iu52i2wSDvo6DcGg@z> (raw) In-Reply-To: <20160413124943.GH14351@dhcp22.suse.cz> On Wed 13-04-16 14:49:43, Michal Hocko wrote: > On Wed 13-04-16 12:27:31, Ingo Molnar wrote: > > > > * Ingo Molnar <mingo@kernel.org> wrote: > > > > > I'm testing your patches today, if they are otherwise OK [...] > > > > got this build failure: > > > > ./arch/x86/include/asm/rwsem.h:106:2: error: ‘asm’ operand has impossible constraints > > Hmm, I have no idea why 64b didn't have problem with the asm but 32b > complains. Anyway, the following makes both happy. I have checked the > generated code for 64b and it hasn't changed after the patch. 32b also > seems to be generating a proper code. My gcc asm()-foo is rather weak so > I would feel better if somebody double checked after me. Peter, Ingo, does the patch makes sense to you? Thanks! > --- > From d23f4e6994670bf2c5d864f2190f21022b4499b2 Mon Sep 17 00:00:00 2001 > From: Michal Hocko <mhocko@suse.com> > Date: Wed, 13 Apr 2016 14:21:25 +0200 > Subject: [PATCH] x86: __down_read_trylock fix 32b build failure > MIME-Version: 1.0 > Content-Type: text/plain; charset=UTF-8 > Content-Transfer-Encoding: 8bit > > Ingo has noticed the following compilation error with CONFIG_X86_32=y > ./arch/x86/include/asm/rwsem.h:106:2: error: ‘asm’ operand has impossible constraints > > The reason seems to be that 32b doesn't like ret being input and output > argument sharing the same register with sem which is only the input. Fix > this by making ret output only and use %3 (aka sem) for xadd. > > ret initialization is not needed now because this is done implicitly > by the asm even for the fast path as both sem and ret share the same > register. > > Reported-by: Ingo Molnar <mingo@kernel.org> > Signed-off-by: Michal Hocko <mhocko@suse.com> > --- > arch/x86/include/asm/rwsem.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h > index d759c5f70f49..453744c1d347 100644 > --- a/arch/x86/include/asm/rwsem.h > +++ b/arch/x86/include/asm/rwsem.h > @@ -102,9 +102,9 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) > #define ____down_write(sem, slow_path) \ > ({ \ > long tmp; \ > - struct rw_semaphore* ret = sem; \ > + struct rw_semaphore* ret; \ > asm volatile("# beginning down_write\n\t" \ > - LOCK_PREFIX " xadd %1,(%2)\n\t" \ > + LOCK_PREFIX " xadd %1,(%3)\n\t" \ > /* adds 0xffff0001, returns the old value */ \ > " test " __ASM_SEL(%w1,%k1) "," __ASM_SEL(%w1,%k1) "\n\t" \ > /* was the active mask 0 before? */\ > @@ -112,7 +112,7 @@ static inline int __down_read_trylock(struct rw_semaphore *sem) > " call " slow_path "\n" \ > "1:\n" \ > "# ending down_write" \ > - : "+m" (sem->count), "=d" (tmp), "+a" (ret) \ > + : "+m" (sem->count), "=d" (tmp), "=a" (ret) \ > : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS) \ > : "memory", "cc"); \ > ret; \ > -- > 2.8.0.rc3 > > -- > Michal Hocko > SUSE Labs -- Michal Hocko SUSE Labs
next prev parent reply other threads:[~2016-04-17 16:59 UTC|newest] Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-04-07 15:12 [PATCH 0/11] introduce down_write_killable for rw_semaphore v3 Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-07 15:12 ` [PATCH 01/11] locking, rwsem: get rid of __down_write_nested Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-07 15:12 ` [PATCH 02/11] locking, rwsem: drop explicit memory barriers Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-07 15:12 ` [PATCH 03/11] xtensa, rwsem: drop superfluous arch specific implementation Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-07 15:12 ` [PATCH 04/11] sh, " Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-07 15:12 ` [PATCH 05/11] sparc, " Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-07 15:12 ` [PATCH 06/11] locking, rwsem: introduce basis for down_write_killable Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-07 15:12 ` [PATCH 07/11] alpha, rwsem: provide __down_write_killable Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-07 15:12 ` [PATCH 08/11] ia64, " Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-07 17:28 ` Sergei Shtylyov 2016-04-08 6:22 ` Michal Hocko 2016-04-07 15:12 ` [PATCH 09/11] s390, " Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-07 15:12 ` [PATCH 10/11] x86, " Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-13 9:08 ` Ingo Molnar 2016-04-13 9:16 ` Michal Hocko 2016-04-13 9:16 ` Michal Hocko 2016-04-13 9:19 ` Ingo Molnar 2016-04-13 9:19 ` Ingo Molnar 2016-04-13 10:27 ` Ingo Molnar 2016-04-13 12:49 ` Michal Hocko 2016-04-13 12:49 ` Michal Hocko 2016-04-17 16:59 ` Michal Hocko [this message] 2016-04-17 16:59 ` Michal Hocko 2016-04-20 13:40 ` Peter Zijlstra 2016-04-20 13:40 ` Peter Zijlstra 2016-04-20 18:04 ` H. Peter Anvin 2016-04-20 18:04 ` H. Peter Anvin 2016-04-20 20:45 ` Borislav Petkov 2016-04-20 20:45 ` Borislav Petkov 2016-04-20 20:58 ` Michal Hocko 2016-04-20 20:58 ` Michal Hocko 2016-04-20 21:06 ` H. Peter Anvin 2016-04-20 21:06 ` H. Peter Anvin 2016-04-20 21:36 ` Borislav Petkov 2016-04-20 22:29 ` H. Peter Anvin 2016-04-20 22:29 ` H. Peter Anvin 2016-04-21 11:35 ` Borislav Petkov 2016-04-21 11:35 ` Borislav Petkov 2016-04-21 13:09 ` Michal Hocko 2016-04-21 13:09 ` Michal Hocko 2016-04-21 13:21 ` Borislav Petkov 2016-04-21 13:21 ` Borislav Petkov 2016-04-27 12:02 ` [PATCH] x86/locking/rwsem: Cleanup ____down_write() Borislav Petkov 2016-04-27 12:02 ` Borislav Petkov 2016-04-22 6:53 ` [PATCH 10/11] x86, rwsem: provide __down_write_killable Ingo Molnar 2016-04-22 6:53 ` Ingo Molnar 2016-04-13 9:57 ` [PATCH] x86: add frame annotation for call_rwsem_down_write_failed_killable Michal Hocko 2016-04-07 15:12 ` [PATCH 11/11] locking, rwsem: provide down_write_killable Michal Hocko 2016-04-07 15:12 ` Michal Hocko 2016-04-12 9:37 ` [PATCH 0/11] introduce down_write_killable for rw_semaphore v3 Michal Hocko 2016-04-12 9:37 ` Michal Hocko 2016-04-12 15:40 ` Peter Zijlstra 2016-04-12 15:40 ` Peter Zijlstra 2016-04-12 18:01 ` Michal Hocko 2016-04-12 18:01 ` Michal Hocko -- strict thread matches above, loose matches on Subject: below -- 2016-04-01 11:04 [PATCH 0/11] introduce down_write_killable for rw_semaphore v2 Michal Hocko 2016-04-01 11:04 ` [PATCH 10/11] x86, rwsem: provide __down_write_killable Michal Hocko 2016-04-06 18:31 ` Peter Zijlstra 2016-02-29 12:58 [PATCH 0/11] introduce down_write_killable for rw_semaphore Michal Hocko 2016-02-29 12:58 ` [PATCH 10/11] x86, rwsem: provide __down_write_killable Michal Hocko
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