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| author | Florian Weimer <fweimer@redhat.com> | 2021-07-09 10:59:22 +0200 |
|---|---|---|
| committer | Florian Weimer <fweimer@redhat.com> | 2021-07-09 10:59:22 +0200 |
| commit | 508ee037a30f1d4f6a1f8de2bd0d9866d4684625 (patch) | |
| tree | 7784739365084bd7bef3913e01e58f31b7599ad5 | |
| parent | 01d780628278972cfa3630feeb74d7861b0fd5fc (diff) | |
| download | glibc-508ee037a30f1d4f6a1f8de2bd0d9866d4684625.tar glibc-508ee037a30f1d4f6a1f8de2bd0d9866d4684625.tar.gz glibc-508ee037a30f1d4f6a1f8de2bd0d9866d4684625.tar.bz2 glibc-508ee037a30f1d4f6a1f8de2bd0d9866d4684625.zip | |
nptl: Use out-of-line wake function in __libc_lock_unlock slow path
This slightly reduces code size, as can be seen below.
__libc_lock_unlock is usually used along with __libc_lock_lock in
the same function. __libc_lock_lock already has an out-of-line
slow path, so this change should not introduce many additional
non-leaf functions.
This change also fixes a link failure in 32-bit Arm thumb mode
because commit 1f9c804fbd699104adefbce9e56d2c8aa711b6b9
("nptl: Use internal low-level lock type for !IS_IN (libc)")
introduced __libc_do_syscall calls outside of libc.
Before x86-64:
text data bss dec hex filename
1937748 20456 54896 2013100 1eb7ac libc.so.6
25601 856 12768 39225 9939 nss/libnss_db.so.2
40310 952 25144 66406 10366 nss/libnss_files.so.2
After x86-64:
text data bss dec hex filename
1935312 20456 54896 2010664 1eae28 libc.so.6
25559 864 12768 39191 9917 nss/libnss_db.so.2
39764 960 25144 65868 1014c nss/libnss_files.so.2
Before i686:
2110961 11272 39144 2161377 20fae1 libc.so.6
27243 428 12652 40323 9d83 nss/libnss_db.so.2
43062 476 25028 68566 10bd6 nss/libnss_files.so.2
After i686:
2107347 11272 39144 2157763 20ecc3 libc.so.6
26929 432 12652 40013 9c4d nss/libnss_db.so.2
43132 480 25028 68640 10c20 nss/libnss_files.so.2
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
| -rw-r--r-- | nptl/Versions | 1 | ||||
| -rw-r--r-- | nptl/lowlevellock.c | 14 | ||||
| -rw-r--r-- | sysdeps/nptl/lowlevellock.h | 26 |
3 files changed, 33 insertions, 8 deletions
diff --git a/nptl/Versions b/nptl/Versions index 2a75f013f2..3221de89d1 100644 --- a/nptl/Versions +++ b/nptl/Versions @@ -380,6 +380,7 @@ libc { } GLIBC_PRIVATE { __libc_alloca_cutoff; + __lll_lock_wake_private; __lll_lock_wait_private; __nptl_create_event; __nptl_death_event; diff --git a/nptl/lowlevellock.c b/nptl/lowlevellock.c index 2d077d8694..4f88178964 100644 --- a/nptl/lowlevellock.c +++ b/nptl/lowlevellock.c @@ -52,6 +52,20 @@ __lll_lock_wait (int *futex, int private) } libc_hidden_def (__lll_lock_wait) +void +__lll_lock_wake_private (int *futex) +{ + lll_futex_wake (futex, 1, LLL_PRIVATE); +} +libc_hidden_def (__lll_lock_wake_private) + +void +__lll_lock_wake (int *futex, int private) +{ + lll_futex_wake (futex, 1, private); +} +libc_hidden_def (__lll_lock_wake) + #if ENABLE_ELISION_SUPPORT int __pthread_force_elision __attribute__ ((nocommon)); libc_hidden_data_def (__pthread_force_elision) diff --git a/sysdeps/nptl/lowlevellock.h b/sysdeps/nptl/lowlevellock.h index be60c9ac28..4d95114ed3 100644 --- a/sysdeps/nptl/lowlevellock.h +++ b/sysdeps/nptl/lowlevellock.h @@ -125,6 +125,11 @@ libc_hidden_proto (__lll_lock_wait) #define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private) +extern void __lll_lock_wake_private (int *futex); +libc_hidden_proto (__lll_lock_wake_private) +extern void __lll_lock_wake (int *futex, int private); +libc_hidden_proto (__lll_lock_wake) + /* This is an expression rather than a statement even though its value is void, so that it can be used in a comma expression or as an expression that's cast to void. */ @@ -137,14 +142,19 @@ libc_hidden_proto (__lll_lock_wait) acquires the lock and when there will be no further lock acquisitions; thus, we must not access the lock after releasing it, or those accesses could be concurrent with mutex destruction or reuse of the memory. */ -#define __lll_unlock(futex, private) \ - ((void) \ - ({ \ - int *__futex = (futex); \ - int __private = (private); \ - int __oldval = atomic_exchange_rel (__futex, 0); \ - if (__glibc_unlikely (__oldval > 1)) \ - lll_futex_wake (__futex, 1, __private); \ +#define __lll_unlock(futex, private) \ + ((void) \ + ({ \ + int *__futex = (futex); \ + int __private = (private); \ + int __oldval = atomic_exchange_rel (__futex, 0); \ + if (__glibc_unlikely (__oldval > 1)) \ + { \ + if (__builtin_constant_p (private) && (private) == LLL_PRIVATE) \ + __lll_lock_wake_private (__futex); \ + else \ + __lll_lock_wake (__futex, __private); \ + } \ })) #define lll_unlock(futex, private) \ __lll_unlock (&(futex), private) |