[PATCH 1/3] UML - Add TIF_RESTORE_SIGMASK support

From: Jeff Dike
Date: Sun Jan 15 2006 - 00:41:09 EST

Add support for TIF_RESTORE_SIGMASK. I copy the i386 handling of the flag.
sys_sigsuspend is also changed to follow i386.
Also a bit of cleanup -
turn an if into a switch
get rid of a couple more emacs formatting comments

Signed-off-by: Jeff Dike <jdike@xxxxxxxxxxx>

Index: linux-2.6.15-mm/arch/um/kernel/signal_kern.c
===================================================================
--- linux-2.6.15-mm.orig/arch/um/kernel/signal_kern.c 2006-01-14 18:50:04.000000000 -0500
+++ linux-2.6.15-mm/arch/um/kernel/signal_kern.c 2006-01-14 18:56:57.000000000 -0500
@@ -99,31 +99,46 @@ static int handle_signal(struct pt_regs
return err;
}

-static int kern_do_signal(struct pt_regs *regs, sigset_t *oldset)
+static int kern_do_signal(struct pt_regs *regs)
{
struct k_sigaction ka_copy;
siginfo_t info;
+ sigset_t *oldset;
int sig, handled_sig = 0;

+ if (test_thread_flag(TIF_RESTORE_SIGMASK))
+ oldset = &current->saved_sigmask;
+ else
+ oldset = &current->blocked;
+
while((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0){
handled_sig = 1;
/* Whee! Actually deliver the signal. */
- if(!handle_signal(regs, sig, &ka_copy, &info, oldset))
+ if(!handle_signal(regs, sig, &ka_copy, &info, oldset)){
+ /* a signal was successfully delivered; the saved
+ * sigmask will have been stored in the signal frame,
+ * and will be restored by sigreturn, so we can simply
+ * clear the TIF_RESTORE_SIGMASK flag */
+ if (test_thread_flag(TIF_RESTORE_SIGMASK))
+ clear_thread_flag(TIF_RESTORE_SIGMASK);
break;
+ }
}

/* Did we come from a system call? */
if(!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)){
/* Restart the system call - no handlers present */
- if(PT_REGS_SYSCALL_RET(regs) == -ERESTARTNOHAND ||
- PT_REGS_SYSCALL_RET(regs) == -ERESTARTSYS ||
- PT_REGS_SYSCALL_RET(regs) == -ERESTARTNOINTR){
+ switch(PT_REGS_SYSCALL_RET(regs)){
+ case -ERESTARTNOHAND:
+ case -ERESTARTSYS:
+ case -ERESTARTNOINTR:
PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
PT_REGS_RESTART_SYSCALL(regs);
- }
- else if(PT_REGS_SYSCALL_RET(regs) == -ERESTART_RESTARTBLOCK){
+ break;
+ case -ERESTART_RESTARTBLOCK:
PT_REGS_SYSCALL_RET(regs) = __NR_restart_syscall;
PT_REGS_RESTART_SYSCALL(regs);
+ break;
}
}

@@ -137,12 +152,19 @@ static int kern_do_signal(struct pt_regs
if(current->ptrace & PT_DTRACE)
current->thread.singlestep_syscall =
is_syscall(PT_REGS_IP(&current->thread.regs));
+
+ /* if there's no signal to deliver, we just put the saved sigmask
+ * back */
+ if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) {
+ clear_thread_flag(TIF_RESTORE_SIGMASK);
+ sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
+ }
return(handled_sig);
}

int do_signal(void)
{
- return(kern_do_signal(&current->thread.regs, &current->blocked));
+ return(kern_do_signal(&current->thread.regs));
}

/*
@@ -150,27 +172,22 @@ int do_signal(void)
*/
long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
{
- sigset_t saveset;
-
mask &= _BLOCKABLE;
spin_lock_irq(&current->sighand->siglock);
- saveset = current->blocked;
+ current->saved_sigmask = current->blocked;
siginitset(&current->blocked, mask);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);

- PT_REGS_SYSCALL_RET(&current->thread.regs) = -EINTR;
- while (1) {
- current->state = TASK_INTERRUPTIBLE;
- schedule();
- if(kern_do_signal(&current->thread.regs, &saveset))
- return(-EINTR);
- }
+ current->state = TASK_INTERRUPTIBLE;
+ schedule();
+ set_thread_flag(TIF_RESTORE_SIGMASK);
+ return -ERESTARTNOHAND;
}

long sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize)
{
- sigset_t saveset, newset;
+ sigset_t newset;

/* XXX: Don't preclude handling different sized sigset_t's. */
if (sigsetsize != sizeof(sigset_t))
@@ -181,32 +198,18 @@ long sys_rt_sigsuspend(sigset_t __user *
sigdelsetmask(&newset, ~_BLOCKABLE);

spin_lock_irq(&current->sighand->siglock);
- saveset = current->blocked;
+ current->saved_sigmask = current->blocked;
current->blocked = newset;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);

- PT_REGS_SYSCALL_RET(&current->thread.regs) = -EINTR;
- while (1) {
- current->state = TASK_INTERRUPTIBLE;
- schedule();
- if (kern_do_signal(&current->thread.regs, &saveset))
- return(-EINTR);
- }
+ current->state = TASK_INTERRUPTIBLE;
+ schedule();
+ set_thread_flag(TIF_RESTORE_SIGMASK);
+ return -ERESTARTNOHAND;
}

long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
{
return(do_sigaltstack(uss, uoss, PT_REGS_SP(&current->thread.regs)));
}
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only. This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
Index: linux-2.6.15-mm/include/asm-um/thread_info.h
===================================================================
--- linux-2.6.15-mm.orig/include/asm-um/thread_info.h 2006-01-14 18:14:20.000000000 -0500
+++ linux-2.6.15-mm/include/asm-um/thread_info.h 2006-01-14 18:58:15.000000000 -0500
@@ -69,6 +69,7 @@ static inline struct thread_info *curren
#define TIF_RESTART_BLOCK 4
#define TIF_MEMDIE 5
#define TIF_SYSCALL_AUDIT 6
+#define TIF_RESTORE_SIGMASK 7

#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
@@ -76,16 +77,6 @@ static inline struct thread_info *curren
#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
#define _TIF_MEMDIE (1 << TIF_MEMDIE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
+#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)

#endif
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only. This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */

-
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