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| author | Torvald Riegel <triegel@redhat.com> | 2012-01-24 19:17:05 +0000 |
|---|---|---|
| committer | Torvald Riegel <torvald@gcc.gnu.org> | 2012-01-24 19:17:05 +0000 |
| commit | 999bcff5bd185eca61a9781c043a56f06b133366 (patch) | |
| tree | e26e3ce6a636f90d893869eb973d01b436295141 | |
| parent | c873934cd90496aa07712b257b6ae6e8027d952f (diff) | |
| download | gcc-999bcff5bd185eca61a9781c043a56f06b133366.zip gcc-999bcff5bd185eca61a9781c043a56f06b133366.tar.gz gcc-999bcff5bd185eca61a9781c043a56f06b133366.tar.bz2 | |
libitm: Fix wake-up of readers in futex-based serial lock.
libitm/
* config/linux/rwlock.cc (GTM::gtm_rwlock::write_unlock): Fix reader
wake-up.
From-SVN: r183488
| -rw-r--r-- | libitm/ChangeLog | 5 | ||||
| -rw-r--r-- | libitm/config/linux/rwlock.cc | 9 |
2 files changed, 11 insertions, 3 deletions
diff --git a/libitm/ChangeLog b/libitm/ChangeLog index 4b6d156..9da73d0 100644 --- a/libitm/ChangeLog +++ b/libitm/ChangeLog @@ -1,3 +1,8 @@ +2012-01-24 Torvald Riegel <triegel@redhat.com> + + * config/linux/rwlock.cc (GTM::gtm_rwlock::write_unlock): Fix reader + wake-up. + 2012-01-24 Uros Bizjak <ubizjak@gmail.com> * config/x86/target.h (gtm_jmpbuf) [__x86_64__]: Move rip to the diff --git a/libitm/config/linux/rwlock.cc b/libitm/config/linux/rwlock.cc index 24e7042..ad1b042 100644 --- a/libitm/config/linux/rwlock.cc +++ b/libitm/config/linux/rwlock.cc @@ -231,10 +231,13 @@ gtm_rwlock::write_unlock () // last writer (this can happen because write_lock_generic() // exchanges 0 or 1 to 2 and thus might go to contended mode even if // no other thread holds the write lock currently). Therefore, we - // have to wake up readers here as well. - futex_wake(&readers, INT_MAX); + // have to wake up readers here as well. Execute a barrier after + // the previous relaxed reset of writers (Dekker-style), and fall + // through to the normal reader wake-up code. + atomic_thread_fence (memory_order_seq_cst); } - return; + else + return; } // No waiting writers, so wake up all waiting readers. // Because the fetch_and_sub is a full barrier already, we don't need |