https://bugzilla.kernel.org/show_bug.cgi?id=25292 Summary: async-signal-safe functions list in Linux Product: Documentation Version: unspecified Platform: All OS/Version: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: man-pages AssignedTo: documentation_man-pages@xxxxxxxxxxxxxxxxxxxx ReportedBy: kosaki.motohiro@xxxxxxxxxxxxxx Regression: No Signal(7) described which functions are async-signal-safe. But it is only written POSIX definition, is not described linux implementation specific limit. And it should be. I have three example. 1. fork glibc malloc are calling pthread_atfork() internally, therefore our fork is async signal unsafe since long time ago. http://sourceware.org/bugzilla/show_bug.cgi?id=4737 The standard comitte has decided to remove fork() from async-signal-safe functions in future standard. (see following defect reports) http://www.opengroup.org/austin/aardvark/latest/xshbug3.txt > _____________________________________________________________________________ > COMMENT Enhancement Request Number 15 > rajani.g.k:xxxxxx Defect in XSH 2.4.3 (rdvk# 6) > {GKRFORK012009} Thu, 8 Jan 2009 07:41:10 GMT > _____________________________________________________________________________ > Accept_____ Accept as marked below_X___ Duplicate_____ Reject_____ > Rationale for rejected or partial changes: > > We agreed not to send this down the interps track yet. > > The standard is clear and concerns are being forwarded to the sponsor. > A previous interpretation 1003.1c-1995 #37, and also ERN XSHbug2145 have > addressed the same issue, but still the problem has remained unresolved. > > Because of the problems which exist here it has become > clear that an application using pthread_atfork(), even if the application itself > did not call pthread_atfork(), may have had pthread_atfork() handlers > installed by a third party library or the implementation. Therefore > calling fork() from an asynchronous signal handler is undefined. > Therefore we are removing fork() from the list of > async-signal-safe functions. > > > Recommendations for a future revision: > A future revision should mandate posix_spawn() and add that to the list > of async-signal-safe functions. > Remove fork() from the list of async-signal-safe functions. > [ 12 Feb 2009 - we had no consensus on the changes for a future revision] 2. aio_suspend It is using pthread_mutex_lock() internally. glibc/sysdeps/pthread/aio_suspend.c ------------------------------------------ int aio_suspend (list, nent, timeout) const struct aiocb *const list[]; int nent; const struct timespec *timeout; { (snip) /* Request the mutex. */ pthread_mutex_lock (&__aio_requests_mutex); 3. execle It is using realloc internally. glibc/posix/execle.c ---------------------------------------------------------- int execle (const char *path, const char *arg, ...) { #define INITIAL_ARGV_MAX 1024 size_t argv_max = INITIAL_ARGV_MAX; const char *initial_argv[INITIAL_ARGV_MAX]; const char **argv = initial_argv; va_list args; argv[0] = arg; va_start (args, arg); unsigned int i = 0; while (argv[i++] != NULL) { if (i == argv_max) { argv_max *= 2; const char **nptr = realloc (argv == initial_argv ? NULL : argv, argv_max * sizeof (const char *)); if (nptr == NULL) { Can you please consider to update signal(7) man page? -- Configure bugmail: https://bugzilla.kernel.org/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are watching the assignee of the bug. -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
