Re: [PATCH] PPC32: cancel syscall restart on signal delivery

[Linus Torvalds]

On Sat, 15 Nov 2003, Paul Mackerras wrote:
> 
> Now, when we resume that context we will call sys_restart_syscall
> which will call restart_block.fn.  Which won't necessarily still point
> to do_no_restart_syscall.  So I still think we have a problem.

Excellent point. We're actually much better off resetting it at signal
return.

Which should make all other resets unnecessary.

Yes, you can get out of a signal by using longjmp, but that doesn't
matter: you can't longjump to a restart call (well, you can, but only if
the user literally tries to do the restart by hand, ie he _intended_ to do
it).

So the _proper_ fix (for x86) should be as appended. Agreed?

		Linus

----
===== arch/i386/kernel/signal.c 1.33 vs edited =====
--- 1.33/arch/i386/kernel/signal.c	Tue Nov 11 21:18:46 2003
+++ edited/arch/i386/kernel/signal.c	Fri Nov 14 21:13:09 2003
@@ -132,6 +132,9 @@
 {
 	unsigned int err = 0;
 
+	/* Always make any pending restarted system calls return -EINTR */
+	current_thread_info()->restart_block.fn = do_no_restart_syscall;
+
 #define COPY(x)		err |= __get_user(regs->x, &sc->x)
 
 #define COPY_SEG(seg)							\
@@ -503,9 +506,6 @@
 	struct pt_regs * regs)
 {
 	struct k_sigaction *ka = &current->sighand->action[sig-1];
-
-	/* Always make any pending restarted system calls return -EINTR */
-	current_thread_info()->restart_block.fn = do_no_restart_syscall;
 
 	/* Are we from a system call? */
 	if (regs->orig_eax >= 0) {

-
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