From 23f12d0a815e55ab60a0e6d973fc3f4730ca6980 Mon Sep 17 00:00:00 2001 From: Paul Murphy Date: Thu, 27 Aug 2015 09:48:04 -0500 Subject: powerpc: Fix usage of elision transient failure adapt param The skip_lock_out_of_tbegin_retries adaptive parameter was not being used correctly, nor as described. This prevents a fallback for all users of the lock if a transient abort occurs within the accepted number of retries. [BZ #19174] * sysdeps/powerpc/nptl/elide.h (__elide_lock): Fix usage of .skip_lock_out_of_tbegin_retries. * sysdeps/unix/sysv/linux/powerpc/elision-lock.c (__lll_lock_elision): Likewise, and respect a value of try_tbegin <= 0. (cherry picked from commit 72f1463df85a522bfd1568e47bd81371522ee358) Conflicts: NEWS (cherry picked from commit cd51b1424477652cccdb83e7a95644d198fd4513) --- sysdeps/powerpc/nptl/elide.h | 6 +++--- sysdeps/unix/sysv/linux/powerpc/elision-lock.c | 15 ++++++--------- 2 files changed, 9 insertions(+), 12 deletions(-) diff --git a/sysdeps/powerpc/nptl/elide.h b/sysdeps/powerpc/nptl/elide.h index 12171f45dc..2e1e443278 100644 --- a/sysdeps/powerpc/nptl/elide.h +++ b/sysdeps/powerpc/nptl/elide.h @@ -27,7 +27,7 @@ configurations. Returns true if the system should retry again or false otherwise. */ static inline bool -__get_new_count (uint8_t *adapt_count) +__get_new_count (uint8_t *adapt_count, int attempt) { /* A persistent failure indicates that a retry will probably result in another failure. Use normal locking now and @@ -40,7 +40,7 @@ __get_new_count (uint8_t *adapt_count) } /* Same logic as above, but for a number of temporary failures in a a row. */ - else if (__elision_aconf.skip_lock_out_of_tbegin_retries > 0 + else if (attempt <= 1 && __elision_aconf.skip_lock_out_of_tbegin_retries > 0 && __elision_aconf.try_tbegin > 0) *adapt_count = __elision_aconf.skip_lock_out_of_tbegin_retries; return true; @@ -78,7 +78,7 @@ __get_new_count (uint8_t *adapt_count) __builtin_tabort (_ABORT_LOCK_BUSY); \ } \ else \ - if (!__get_new_count(&adapt_count)) \ + if (!__get_new_count (&adapt_count,i)) \ break; \ } \ ret; \ diff --git a/sysdeps/unix/sysv/linux/powerpc/elision-lock.c b/sysdeps/unix/sysv/linux/powerpc/elision-lock.c index 7f9bcc2bf1..c6731ca6a4 100644 --- a/sysdeps/unix/sysv/linux/powerpc/elision-lock.c +++ b/sysdeps/unix/sysv/linux/powerpc/elision-lock.c @@ -72,8 +72,7 @@ __lll_lock_elision (int *lock, short *adapt_count, EXTRAARG int pshared) goto use_lock; } - int try_begin = aconf.try_tbegin; - while (1) + for (int i = aconf.try_tbegin; i > 0; i--) { if (__builtin_tbegin (0)) { @@ -87,21 +86,19 @@ __lll_lock_elision (int *lock, short *adapt_count, EXTRAARG int pshared) /* A persistent failure indicates that a retry will probably result in another failure. Use normal locking now and for the next couple of calls. */ - if (try_begin-- <= 0 - || _TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ())) + if (_TEXASRU_FAILURE_PERSISTENT (__builtin_get_texasru ())) { if (aconf.skip_lock_internal_abort > 0) *adapt_count = aconf.skip_lock_internal_abort; goto use_lock; } - /* Same logic as above, but for for a number of temporary failures - in a row. */ - else if (aconf.skip_lock_out_of_tbegin_retries > 0 - && aconf.try_tbegin > 0) - *adapt_count = aconf.skip_lock_out_of_tbegin_retries; } } + /* Fall back to locks for a bit if retries have been exhausted */ + if (aconf.try_tbegin > 0 && aconf.skip_lock_out_of_tbegin_retries > 0) + *adapt_count = aconf.skip_lock_out_of_tbegin_retries; + use_lock: return LLL_LOCK ((*lock), pshared); } -- cgit 1.4.1