[10/11] x86, rwsem: provide __down_write_killable
diff mbox

Message ID 1460041951-22347-11-git-send-email-mhocko@kernel.org
State New
Headers show

Commit Message

Michal Hocko April 7, 2016, 3:12 p.m. UTC
From: Michal Hocko <mhocko@suse.com>

which uses the same fast path as __down_write except it falls back to
call_rwsem_down_write_failed_killable slow path and return -EINTR if
killed. To prevent from code duplication extract the skeleton of
__down_write into a helper macro which just takes the semaphore
and the slow path function to be called.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 arch/x86/include/asm/rwsem.h | 41 ++++++++++++++++++++++++++++-------------
 arch/x86/lib/rwsem.S         |  8 ++++++++
 2 files changed, 36 insertions(+), 13 deletions(-)

Comments

Ingo Molnar April 13, 2016, 9:08 a.m. UTC | #1
* Michal Hocko <mhocko@kernel.org> wrote:

> From: Michal Hocko <mhocko@suse.com>
> 
> which uses the same fast path as __down_write except it falls back to
> call_rwsem_down_write_failed_killable slow path and return -EINTR if
> killed. To prevent from code duplication extract the skeleton of
> __down_write into a helper macro which just takes the semaphore
> and the slow path function to be called.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  arch/x86/include/asm/rwsem.h | 41 ++++++++++++++++++++++++++++-------------
>  arch/x86/lib/rwsem.S         |  8 ++++++++
>  2 files changed, 36 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
> index d79a218675bc..4c3d90dbe89a 100644
> --- a/arch/x86/include/asm/rwsem.h
> +++ b/arch/x86/include/asm/rwsem.h
> @@ -99,21 +99,36 @@ static inline int __down_read_trylock(struct rw_semaphore *sem)
>  /*
>   * lock for writing
>   */
> +#define ____down_write(sem, slow_path)			\
> +({							\
> +	long tmp;					\
> +	struct rw_semaphore* ret = sem;			\
> +	asm volatile("# beginning down_write\n\t"	\
> +		     LOCK_PREFIX "  xadd      %1,(%2)\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? */\
> +		     "  jz        1f\n"			\
> +		     "  call " slow_path "\n"		\
> +		     "1:\n"				\
> +		     "# ending down_write"		\
> +		     : "+m" (sem->count), "=d" (tmp), "+a" (ret)	\
> +		     : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS) \
> +		     : "memory", "cc");			\
> +	ret;						\
> +})
> +
>  static inline void __down_write(struct rw_semaphore *sem)
>  {
> -	long tmp;
> -	asm volatile("# beginning down_write\n\t"
> -		     LOCK_PREFIX "  xadd      %1,(%2)\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? */
> -		     "  jz        1f\n"
> -		     "  call call_rwsem_down_write_failed\n"
> -		     "1:\n"
> -		     "# ending down_write"
> -		     : "+m" (sem->count), "=d" (tmp)
> -		     : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS)
> -		     : "memory", "cc");
> +	____down_write(sem, "call_rwsem_down_write_failed");
> +}
> +
> +static inline int __down_write_killable(struct rw_semaphore *sem)
> +{
> +	if (IS_ERR(____down_write(sem, "call_rwsem_down_write_failed_killable")))
> +		return -EINTR;
> +
> +	return 0;
>  }
>  
>  /*
> diff --git a/arch/x86/lib/rwsem.S b/arch/x86/lib/rwsem.S
> index 40027db99140..d1a1397e1fb3 100644
> --- a/arch/x86/lib/rwsem.S
> +++ b/arch/x86/lib/rwsem.S
> @@ -101,6 +101,14 @@ ENTRY(call_rwsem_down_write_failed)
>  	ret
>  ENDPROC(call_rwsem_down_write_failed)
>  
> +ENTRY(call_rwsem_down_write_failed_killable)
> +	save_common_regs
> +	movq %rax,%rdi
> +	call rwsem_down_write_failed_killable
> +	restore_common_regs
> +	ret
> +ENDPROC(call_rwsem_down_write_failed_killable)

Got this objtool warning on x86-64 allyesconfig:

  arch/x86/lib/rwsem.o: warning: objtool: call_rwsem_down_write_failed_killable()+0xe: call without frame pointer save/setup

Thanks,

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-sh" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Michal Hocko April 13, 2016, 9:16 a.m. UTC | #2
On Wed 13-04-16 11:08:30, Ingo Molnar wrote:
> 
> * Michal Hocko <mhocko@kernel.org> wrote:
[...]
> > +ENTRY(call_rwsem_down_write_failed_killable)
> > +	save_common_regs
> > +	movq %rax,%rdi
> > +	call rwsem_down_write_failed_killable
> > +	restore_common_regs
> > +	ret
> > +ENDPROC(call_rwsem_down_write_failed_killable)
> 
> Got this objtool warning on x86-64 allyesconfig:
> 
>   arch/x86/lib/rwsem.o: warning: objtool: call_rwsem_down_write_failed_killable()+0xe: call without frame pointer save/setup

Peter has already pointed that out. This is because the 4.5 which I was
basing my work on doesn't have 3387a535ce62 ("x86/asm: Create stack
frames in rwsem functions") which shown up in 4.6-rc1. He mentioned to
add the missing FRAME_{BEGIN,END} during the merge AFAIR.

Does that sound reasonable to you or should I rebase?
Ingo Molnar April 13, 2016, 9:19 a.m. UTC | #3
* Michal Hocko <mhocko@kernel.org> wrote:

> On Wed 13-04-16 11:08:30, Ingo Molnar wrote:
> > 
> > * Michal Hocko <mhocko@kernel.org> wrote:
> [...]
> > > +ENTRY(call_rwsem_down_write_failed_killable)
> > > +	save_common_regs
> > > +	movq %rax,%rdi
> > > +	call rwsem_down_write_failed_killable
> > > +	restore_common_regs
> > > +	ret
> > > +ENDPROC(call_rwsem_down_write_failed_killable)
> > 
> > Got this objtool warning on x86-64 allyesconfig:
> > 
> >   arch/x86/lib/rwsem.o: warning: objtool: call_rwsem_down_write_failed_killable()+0xe: call without frame pointer save/setup
> 
> Peter has already pointed that out. This is because the 4.5 which I was
> basing my work on doesn't have 3387a535ce62 ("x86/asm: Create stack
> frames in rwsem functions") which shown up in 4.6-rc1. He mentioned to
> add the missing FRAME_{BEGIN,END} during the merge AFAIR.
> 
> Does that sound reasonable to you or should I rebase?

I'm testing your patches today, if they are otherwise OK then please send a delta 
patch against the tip:locking/rwsem tree I'll push out.

Thanks,

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-sh" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch
diff mbox

diff --git a/arch/x86/include/asm/rwsem.h b/arch/x86/include/asm/rwsem.h
index d79a218675bc..4c3d90dbe89a 100644
--- a/arch/x86/include/asm/rwsem.h
+++ b/arch/x86/include/asm/rwsem.h
@@ -99,21 +99,36 @@  static inline int __down_read_trylock(struct rw_semaphore *sem)
 /*
  * lock for writing
  */
+#define ____down_write(sem, slow_path)			\
+({							\
+	long tmp;					\
+	struct rw_semaphore* ret = sem;			\
+	asm volatile("# beginning down_write\n\t"	\
+		     LOCK_PREFIX "  xadd      %1,(%2)\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? */\
+		     "  jz        1f\n"			\
+		     "  call " slow_path "\n"		\
+		     "1:\n"				\
+		     "# ending down_write"		\
+		     : "+m" (sem->count), "=d" (tmp), "+a" (ret)	\
+		     : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS) \
+		     : "memory", "cc");			\
+	ret;						\
+})
+
 static inline void __down_write(struct rw_semaphore *sem)
 {
-	long tmp;
-	asm volatile("# beginning down_write\n\t"
-		     LOCK_PREFIX "  xadd      %1,(%2)\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? */
-		     "  jz        1f\n"
-		     "  call call_rwsem_down_write_failed\n"
-		     "1:\n"
-		     "# ending down_write"
-		     : "+m" (sem->count), "=d" (tmp)
-		     : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS)
-		     : "memory", "cc");
+	____down_write(sem, "call_rwsem_down_write_failed");
+}
+
+static inline int __down_write_killable(struct rw_semaphore *sem)
+{
+	if (IS_ERR(____down_write(sem, "call_rwsem_down_write_failed_killable")))
+		return -EINTR;
+
+	return 0;
 }
 
 /*
diff --git a/arch/x86/lib/rwsem.S b/arch/x86/lib/rwsem.S
index 40027db99140..d1a1397e1fb3 100644
--- a/arch/x86/lib/rwsem.S
+++ b/arch/x86/lib/rwsem.S
@@ -101,6 +101,14 @@  ENTRY(call_rwsem_down_write_failed)
 	ret
 ENDPROC(call_rwsem_down_write_failed)
 
+ENTRY(call_rwsem_down_write_failed_killable)
+	save_common_regs
+	movq %rax,%rdi
+	call rwsem_down_write_failed_killable
+	restore_common_regs
+	ret
+ENDPROC(call_rwsem_down_write_failed_killable)
+
 ENTRY(call_rwsem_wake)
 	/* do nothing if still outstanding active readers */
 	__ASM_HALF_SIZE(dec) %__ASM_HALF_REG(dx)