From e6fa16ab9c1e9b344428e6fea4d29e3cc4b28fb0 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 27 Apr 2011 20:59:41 +0200 Subject: signal: sigprocmask() should do retarget_shared_pending() In short, almost every changing of current->blocked is wrong, or at least can lead to the unexpected results. For example. Two threads T1 and T2, T1 sleeps in sigtimedwait/pause/etc. kill(tgid, SIG) can pick T2 for TIF_SIGPENDING. If T2 calls sigprocmask() and blocks SIG before it notices the pending signal, nobody else can handle this pending shared signal. I am not sure this is bug, but at least this looks strange imho. T1 should not sleep forever, there is a signal which should wake it up. This patch moves the code which actually changes ->blocked into the new helper, set_current_blocked() and changes this code to call retarget_shared_pending() as exit_signals() does. We should only care about the signals we just blocked, we use "newset & ~current->blocked" as a mask. We do not check !sigisemptyset(newblocked), retarget_shared_pending() is cheap unless mask & shared_pending. Note: for this particular case we could simply change sigprocmask() to return -EINTR if signal_pending(), but then we should change other callers and, more importantly, if we need this fix then set_current_blocked() will have more callers and some of them can't restart. See the next patch as a random example. Signed-off-by: Oleg Nesterov Reviewed-by: Matt Fleming Acked-by: Tejun Heo --- include/linux/signal.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/signal.h') diff --git a/include/linux/signal.h b/include/linux/signal.h index fcd2b14b1932..ba009c167275 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -243,6 +243,7 @@ extern long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info); extern long do_sigpending(void __user *, unsigned long); extern int sigprocmask(int, sigset_t *, sigset_t *); +extern void set_current_blocked(const sigset_t *); extern int show_unhandled_signals; struct pt_regs; -- cgit v1.2.1 From 943df1485a8ff0e600729e082e568ece04d4de9e Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 27 Apr 2011 21:44:14 +0200 Subject: signal: introduce do_sigtimedwait() to factor out compat/native code Factor out the common code in sys_rt_sigtimedwait/compat_sys_rt_sigtimedwait to the new helper, do_sigtimedwait(). Add the comment to document the extra tick we add to timespec_to_jiffies(ts), thanks to Linus who explained this to me. Perhaps it would be better to move compat_sys_rt_sigtimedwait() into signal.c under CONFIG_COMPAT, then we can make do_sigtimedwait() static. Signed-off-by: Oleg Nesterov Acked-by: Tejun Heo Reviewed-by: Matt Fleming --- include/linux/signal.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/signal.h') diff --git a/include/linux/signal.h b/include/linux/signal.h index ba009c167275..782546d661ba 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -242,6 +242,8 @@ extern int __group_send_sig_info(int, struct siginfo *, struct task_struct *); extern long do_rt_tgsigqueueinfo(pid_t tgid, pid_t pid, int sig, siginfo_t *info); extern long do_sigpending(void __user *, unsigned long); +extern int do_sigtimedwait(const sigset_t *, siginfo_t *, + const struct timespec *); extern int sigprocmask(int, sigset_t *, sigset_t *); extern void set_current_blocked(const sigset_t *); extern int show_unhandled_signals; -- cgit v1.2.1 From 702a5073fdb71eb29cd4912575289fb5044c1894 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 27 Apr 2011 22:01:27 +0200 Subject: signal: rename signandsets() to sigandnsets() As Tejun and Linus pointed out, "nand" is the wrong name for "x & ~y", it should be "andn". Rename signandsets() as suggested. Suggested-by: Tejun Heo Signed-off-by: Oleg Nesterov Acked-by: Tejun Heo --- include/linux/signal.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux/signal.h') diff --git a/include/linux/signal.h b/include/linux/signal.h index 782546d661ba..7e2526374fd7 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -123,13 +123,13 @@ _SIG_SET_BINOP(sigorsets, _sig_or) #define _sig_and(x,y) ((x) & (y)) _SIG_SET_BINOP(sigandsets, _sig_and) -#define _sig_nand(x,y) ((x) & ~(y)) -_SIG_SET_BINOP(signandsets, _sig_nand) +#define _sig_andn(x,y) ((x) & ~(y)) +_SIG_SET_BINOP(sigandnsets, _sig_andn) #undef _SIG_SET_BINOP #undef _sig_or #undef _sig_and -#undef _sig_nand +#undef _sig_andn #define _SIG_SET_OP(name, op) \ static inline void name(sigset_t *set) \ -- cgit v1.2.1 From b2b07e4fdbc51383cfc0ba5618c2ddf5c9d038f2 Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 18 May 2011 15:08:03 +0200 Subject: signal: trivial, fix the "timespec declared inside parameter list" warning Fix the compile warning, do_sigtimedwait(struct timespec *) in signal.h needs the forward declaration of timespec. Reported-and-acked-by: Mike Frysinger Signed-off-by: Oleg Nesterov --- include/linux/signal.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/linux/signal.h') diff --git a/include/linux/signal.h b/include/linux/signal.h index 7e2526374fd7..a44e7f062238 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -234,6 +234,9 @@ static inline int valid_signal(unsigned long sig) return sig <= _NSIG ? 1 : 0; } +struct timespec; +struct pt_regs; + extern int next_signal(struct sigpending *pending, sigset_t *mask); extern int do_send_sig_info(int sig, struct siginfo *info, struct task_struct *p, bool group); @@ -248,7 +251,6 @@ extern int sigprocmask(int, sigset_t *, sigset_t *); extern void set_current_blocked(const sigset_t *); extern int show_unhandled_signals; -struct pt_regs; extern int get_signal_to_deliver(siginfo_t *info, struct k_sigaction *return_ka, struct pt_regs *regs, void *cookie); extern void exit_signals(struct task_struct *tsk); -- cgit v1.2.1