The patch titled
x86 rwsem: minor cleanups
has been added to the -mm tree. Its filename is
x86-rwsem-minor-cleanups.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: x86 rwsem: minor cleanups
From: Michel Lespinasse <walken@xxxxxxxxxx>
Clarified few comments and made initialization of %edx/%rdx more uniform
accross __down_write_nested, __up_read and __up_write functions.
Signed-off-by: Michel Lespinasse <walken@xxxxxxxxxx>
Acked-by: David Howells <dhowells@xxxxxxxxxx>
Cc: Mike Waychison <mikew@xxxxxxxxxx>
Cc: Suleiman Souhlal <suleiman@xxxxxxxxxx>
Cc: Ying Han <yinghan@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/rwsem.h | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)
diff -puN arch/x86/include/asm/rwsem.h~x86-rwsem-minor-cleanups arch/x86/include/asm/rwsem.h
--- a/arch/x86/include/asm/rwsem.h~x86-rwsem-minor-cleanups
+++ a/arch/x86/include/asm/rwsem.h
@@ -118,7 +118,7 @@ static inline void __down_read(struct rw
{
asm volatile("# beginning down_read\n\t"
LOCK_PREFIX _ASM_INC "(%1)\n\t"
- /* adds 0x00000001, returns the old value */
+ /* adds 0x00000001 */
" jns 1f\n"
" call call_rwsem_down_read_failed\n"
"1:\n\t"
@@ -156,11 +156,9 @@ static inline int __down_read_trylock(st
static inline void __down_write_nested(struct rw_semaphore *sem, int subclass)
{
rwsem_count_t tmp;
-
- tmp = RWSEM_ACTIVE_WRITE_BIAS;
asm volatile("# beginning down_write\n\t"
LOCK_PREFIX " xadd %1,(%2)\n\t"
- /* subtract 0x0000ffff, returns the old value */
+ /* adds 0xffff0001, returns the old value */
" test %1,%1\n\t"
/* was the count 0 before? */
" jz 1f\n"
@@ -168,7 +166,7 @@ static inline void __down_write_nested(s
"1:\n"
"# ending down_write"
: "+m" (sem->count), "=d" (tmp)
- : "a" (sem), "1" (tmp)
+ : "a" (sem), "1" (RWSEM_ACTIVE_WRITE_BIAS)
: "memory", "cc");
}
@@ -195,16 +193,16 @@ static inline int __down_write_trylock(s
*/
static inline void __up_read(struct rw_semaphore *sem)
{
- rwsem_count_t tmp = -RWSEM_ACTIVE_READ_BIAS;
+ rwsem_count_t tmp;
asm volatile("# beginning __up_read\n\t"
LOCK_PREFIX " xadd %1,(%2)\n\t"
/* subtracts 1, returns the old value */
" jns 1f\n\t"
- " call call_rwsem_wake\n"
+ " call call_rwsem_wake\n" /* expects old value in %edx */
"1:\n"
"# ending __up_read\n"
: "+m" (sem->count), "=d" (tmp)
- : "a" (sem), "1" (tmp)
+ : "a" (sem), "1" (-RWSEM_ACTIVE_READ_BIAS)
: "memory", "cc");
}
@@ -218,7 +216,7 @@ static inline void __up_write(struct rw_
LOCK_PREFIX " xadd %1,(%2)\n\t"
/* substracts 0xffff0001, returns the old value */
" jns 1f\n\t"
- " call call_rwsem_wake\n"
+ " call call_rwsem_wake\n" /* expects old value in %edx */
"1:\n\t"
"# ending __up_write\n"
: "+m" (sem->count), "=d" (tmp)
_
Patches currently in -mm which might be from walken@xxxxxxxxxx are
x86-rwsem-stay-on-fast-path-when-count0-in-__up_write.patch
x86-rwsem-minor-cleanups.patch
rwsem-fully-separate-code-pathes-to-wake-writers-vs-readers.patch
rwsem-lighter-active-count-checks-when-waking-up-readers.patch
rwsem-let-rwsem_waiting_bias-represent-any-number-of-waiting-threads.patch
rwsem-wake-queued-readers-when-writer-blocks-on-active-read-lock.patch
rwsem-smaller-wrappers-around-rwsem_down_failed_common.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
