diff options
Diffstat (limited to 'system/musl/fix-file-locking-race.patch')
| -rw-r--r-- | system/musl/fix-file-locking-race.patch | 54 |
1 files changed, 0 insertions, 54 deletions
diff --git a/system/musl/fix-file-locking-race.patch b/system/musl/fix-file-locking-race.patch deleted file mode 100644 index 2ef91390a..000000000 --- a/system/musl/fix-file-locking-race.patch +++ /dev/null @@ -1,54 +0,0 @@ -From 0db393d3a77bb9f300a356c6a5484fc2dddb161d Mon Sep 17 00:00:00 2001 -From: Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi> -Date: Tue, 18 Sep 2018 10:03:27 +0300 -Subject: fix race condition in file locking - -The condition occurs when -- thread #1 is holding the lock -- thread #2 is waiting for it on __futexwait -- thread #1 is about to release the lock and performs a_swap -- thread #3 enters the __lockfile function and manages to grab the lock - before thread #1 calls __wake, resetting the MAYBE_WAITERS flag -- thread #1 calls __wake -- thread #2 wakes up but goes again to __futexwait as the lock is - held by thread #3 -- thread #3 releases the lock but does not call __wake as the - MAYBE_WAITERS flag is not set - -This condition results in thread #2 not being woken up. This patch fixes -the problem by making the woken up thread ensure that the flag is -properly set before going to sleep again. - -Mainainer's note: This fixes a regression introduced in commit -c21f750727515602a9e84f2a190ee8a0a2aeb2a1. ---- - src/stdio/__lockfile.c | 12 ++++++------ - 1 file changed, 6 insertions(+), 6 deletions(-) - -diff --git a/src/stdio/__lockfile.c b/src/stdio/__lockfile.c -index 2ff75d8a..0dcb2a42 100644 ---- a/src/stdio/__lockfile.c -+++ b/src/stdio/__lockfile.c -@@ -8,13 +8,13 @@ int __lockfile(FILE *f) - int owner = f->lock, tid = __pthread_self()->tid; - if ((owner & ~MAYBE_WAITERS) == tid) - return 0; -- for (;;) { -- owner = a_cas(&f->lock, 0, tid); -- if (!owner) return 1; -- if (a_cas(&f->lock, owner, owner|MAYBE_WAITERS)==owner) break; -+ owner = a_cas(&f->lock, 0, tid); -+ if (!owner) return 1; -+ while ((owner = a_cas(&f->lock, 0, tid|MAYBE_WAITERS))) { -+ if ((owner & MAYBE_WAITERS) || -+ a_cas(&f->lock, owner, owner|MAYBE_WAITERS)==owner) -+ __futexwait(&f->lock, owner|MAYBE_WAITERS, 1); - } -- while ((owner = a_cas(&f->lock, 0, tid|MAYBE_WAITERS))) -- __futexwait(&f->lock, owner, 1); - return 1; - } - --- -cgit v1.2.1 - |