From 102f6a01e249ce4495f1119ae6d963a2a4a53ce5 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sat, 21 Feb 2015 22:05:15 -0500 Subject: [PATCH] add new masked cancellation mode this is a new extension which is presently intended only for experimental and internal libc use. interface and behavior details may change subject to feedback and experience from using it internally. the basic concept for the new PTHREAD_CANCEL_MASKED state is that the first cancellation point to observe the cancellation request fails with an errno value of ECANCELED rather than acting on cancellation, allowing the caller to process the status and choose whether/how to act upon it. --- include/pthread.h | 1 + src/thread/pthread_cancel.c | 24 +++++++++++++++--------- src/thread/pthread_setcancelstate.c | 2 +- 3 files changed, 17 insertions(+), 10 deletions(-) diff --git a/include/pthread.h b/include/pthread.h index 2697e8bc..99a74a53 100644 --- a/include/pthread.h +++ b/include/pthread.h @@ -63,6 +63,7 @@ extern "C" { #define PTHREAD_CANCEL_ENABLE 0 #define PTHREAD_CANCEL_DISABLE 1 +#define PTHREAD_CANCEL_MASKED 2 #define PTHREAD_CANCEL_DEFERRED 0 #define PTHREAD_CANCEL_ASYNCHRONOUS 1 diff --git a/src/thread/pthread_cancel.c b/src/thread/pthread_cancel.c index 66e0817c..1b71aa42 100644 --- a/src/thread/pthread_cancel.c +++ b/src/thread/pthread_cancel.c @@ -2,9 +2,13 @@ #include "syscall.h" #include "libc.h" -void __cancel() +long __cancel() { - pthread_exit(PTHREAD_CANCELED); + pthread_t self = __pthread_self(); + if (self->canceldisable == PTHREAD_CANCEL_ENABLE || self->cancelasync) + pthread_exit(PTHREAD_CANCELED); + self->canceldisable = PTHREAD_CANCEL_DISABLE; + return -ECANCELED; } /* If __syscall_cp_asm has adjusted the stack pointer, it must provide a @@ -23,13 +27,16 @@ long __syscall_cp_c(syscall_arg_t nr, { pthread_t self; long r; + int st; - if (!libc.has_thread_pointer || (self = __pthread_self())->canceldisable) + if (!libc.has_thread_pointer || (st=(self=__pthread_self())->canceldisable) + && (st==PTHREAD_CANCEL_DISABLE || nr==SYS_close)) return __syscall(nr, u, v, w, x, y, z); r = __syscall_cp_asm(&self->cancel, nr, u, v, w, x, y, z); - if (r==-EINTR && nr!=SYS_close && self->cancel && !self->canceldisable) - __cancel(); + if (r==-EINTR && nr!=SYS_close && self->cancel && + self->canceldisable != PTHREAD_CANCEL_DISABLE) + r = __cancel(); return r; } @@ -47,14 +54,13 @@ static void cancel_handler(int sig, siginfo_t *si, void *ctx) extern const char __cp_begin[1], __cp_end[1]; a_barrier(); - if (!self->cancel || self->canceldisable) return; + if (!self->cancel || self->canceldisable == PTHREAD_CANCEL_DISABLE) return; _sigaddset(&uc->uc_sigmask, SIGCANCEL); if (self->cancelasync || ip >= __cp_begin && ip < __cp_end) { - self->canceldisable = 1; - pthread_sigmask(SIG_SETMASK, &uc->uc_sigmask, 0); - __cancel(); + ((char **)&uc->uc_mcontext)[CANCEL_REG_IP] = (char *)__cp_cancel; + return; } __syscall(SYS_tkill, self->tid, SIGCANCEL); diff --git a/src/thread/pthread_setcancelstate.c b/src/thread/pthread_setcancelstate.c index 2268217d..822a1398 100644 --- a/src/thread/pthread_setcancelstate.c +++ b/src/thread/pthread_setcancelstate.c @@ -2,7 +2,7 @@ int __pthread_setcancelstate(int new, int *old) { - if (new > 1U) return EINVAL; + if (new > 2U) return EINVAL; if (!libc.has_thread_pointer) return ENOSYS; struct pthread *self = __pthread_self(); if (old) *old = self->canceldisable; -- 2.25.1