diff options
Diffstat (limited to 'sysdeps/unix/sysv/linux/s390/elision-unlock.c')
| -rw-r--r-- | sysdeps/unix/sysv/linux/s390/elision-unlock.c | 62 |
1 files changed, 0 insertions, 62 deletions
diff --git a/sysdeps/unix/sysv/linux/s390/elision-unlock.c b/sysdeps/unix/sysv/linux/s390/elision-unlock.c deleted file mode 100644 index 11e96abd5f..0000000000 --- a/sysdeps/unix/sysv/linux/s390/elision-unlock.c +++ /dev/null @@ -1,62 +0,0 @@ -/* Commit an elided pthread lock. - Copyright (C) 2014-2025 Free Software Foundation, Inc. - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 of the License, or (at your option) any later version. - - The GNU C Library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library; if not, see - <https://www.gnu.org/licenses/>. */ - -#include <pthreadP.h> -#include <lowlevellock.h> -#include <htm.h> - -int -__lll_unlock_elision(int *futex, short *adapt_count, int private) -{ - /* If the lock is free, we elided the lock earlier. This does not - necessarily mean that we are in a transaction, because the user code may - have closed the transaction, but that is impossible to detect reliably. - Relaxed MO access to futex is sufficient because a correct program - will only release a lock it has acquired; therefore, it must either - changed the futex word's value to something !=0 or it must have used - elision; these are actions by the same thread, so these actions are - sequenced-before the relaxed load (and thus also happens-before the - relaxed load). Therefore, relaxed MO is sufficient. */ - if (atomic_load_relaxed (futex) == 0) - { - __libc_tend (); - } - else - { - /* Update the adapt_count while unlocking before completing the critical - section. adapt_count is accessed concurrently outside of a - transaction or a critical section (e.g. in elision-lock.c). So we need - to use atomic accesses. However, the value of adapt_count is just a - hint, so relaxed MO accesses are sufficient. - If adapt_count would be decremented while locking, multiple - CPUs, trying to lock the acquired mutex, will decrement adapt_count to - zero and another CPU will try to start a transaction, which will be - immediately aborted as the mutex is locked. - The update of adapt_count is done before releasing the lock as POSIX' - mutex destruction requirements disallow accesses to the mutex after it - has been released and thus could have been acquired or destroyed by - another thread. */ - short adapt_count_val = atomic_load_relaxed (adapt_count); - if (adapt_count_val > 0) - atomic_store_relaxed (adapt_count, adapt_count_val - 1); - - lll_unlock ((*futex), private); - } - return 0; -} -libc_hidden_def (__lll_unlock_elision) |