From f84a1e419017b86b4745ae983854b3d57e8c55f1 Mon Sep 17 00:00:00 2001 From: Ulrich Drepper Date: Fri, 15 May 2009 10:12:35 -0700 Subject: [PATCH] No cancel signal in unsafe places. When disabling async cancellation we cannot return from the function call if the thread is canceled. This happens when the cancel bits have been set before async cancel is disabled but the signal hasn't been sent/received yet. Delay for as long as necessary since otherwise the signal might be received in an unsafe context. (cherry picked from commit 1a7f254b4b0590bfab1baa1400705265b1b23b97) --- nptl/ChangeLog | 6 ++++++ nptl/cancellation.c | 14 +++++++++++++- nptl/libc-cancellation.c | 14 +++++++++++++- 3 files changed, 32 insertions(+), 2 deletions(-) diff --git a/nptl/ChangeLog b/nptl/ChangeLog index b83dfd0c9d8..74a2a73666b 100644 --- a/nptl/ChangeLog +++ b/nptl/ChangeLog @@ -1,3 +1,9 @@ +2009-05-15 Ulrich Drepper + + * cancellation.c (__pthread_disable_asynccancel): Don't return if + thread is canceled. + * libc-cancellation.c (__libc_disable_asynccancel): Likewise. + 2009-04-27 Ulrich Drepper * cancellation.c (__pthread_disable_asynccancel): Use THREAD_ATOMIC_AND diff --git a/nptl/cancellation.c b/nptl/cancellation.c index 81134a679a9..4d528cfc2f6 100644 --- a/nptl/cancellation.c +++ b/nptl/cancellation.c @@ -70,15 +70,17 @@ __pthread_disable_asynccancel (int oldtype) return; struct pthread *self = THREAD_SELF; + int newval; #ifdef THREAD_ATOMIC_AND THREAD_ATOMIC_AND (self, cancelhandling, ~CANCELTYPE_BITMASK); + newval = THREAD_GETMEM (self, cancelhandling); #else int oldval = THREAD_GETMEM (self, cancelhandling); while (1) { - int newval = oldval & ~CANCELTYPE_BITMASK; + newval = oldval & ~CANCELTYPE_BITMASK; if (newval == oldval) break; @@ -92,4 +94,14 @@ __pthread_disable_asynccancel (int oldtype) oldval = curval; } #endif + + /* We cannot return when we are being canceled. Upon return the + thread might be things which would have to be undone. The + following loop should loop until the cancellation signal is + delivered. */ + while (__builtin_expect (newval & CANCELED_BITMASK, 0)) + { + lll_futex_wait (&self->cancelhandling, newval, LLL_PRIVATE); + newval = THREAD_GETMEM (self, cancelhandling); + } } diff --git a/nptl/libc-cancellation.c b/nptl/libc-cancellation.c index cf24f1c0f21..35ac82b3d1b 100644 --- a/nptl/libc-cancellation.c +++ b/nptl/libc-cancellation.c @@ -86,15 +86,17 @@ __libc_disable_asynccancel (int oldtype) return; struct pthread *self = THREAD_SELF; + int newval; #ifdef THREAD_ATOMIC_AND THREAD_ATOMIC_AND (self, cancelhandling, ~CANCELTYPE_BITMASK); + newval = THREAD_GETMEM (self, cancelhandling); #else int oldval = THREAD_GETMEM (self, cancelhandling); while (1) { - int newval = oldval & ~CANCELTYPE_BITMASK; + newval = oldval & ~CANCELTYPE_BITMASK; if (newval == oldval) break; @@ -108,6 +110,16 @@ __libc_disable_asynccancel (int oldtype) oldval = curval; } #endif + + /* We cannot return when we are being canceled. Upon return the + thread might be things which would have to be undone. The + following loop should loop until the cancellation signal is + delivered. */ + while (__builtin_expect (newval & CANCELED_BITMASK, 0)) + { + lll_futex_wait (&self->cancelhandling, newval, LLL_PRIVATE); + newval = THREAD_GETMEM (self, cancelhandling); + } } -- 2.47.2