Hi Al, On Thursday 24 January 2013 04:20 PM, Vineet Gupta wrote: > Per Al Viro's "signals for dummies" https://lkml.org/lkml/2012/12/6/366 > there are 3 golden rules for (not) restarting syscalls: > > " What we need to guarantee is > * restarts do not happen on signals caught in interrupts or exceptions > * restarts do not happen on signals caught in sigreturn() > * restart should happen only once, even if we get through do_signal() > many times." > > ARC Port already handled #1, this patch fixes #2 and #3. > > We use the additional state in pt_regs->orig_r8 to ckh if restarting > has already been done once. > > Thanks to Al Viro for spotting this. > > Signed-off-by: Vineet Gupta <vgupta@xxxxxxxxxxxx> > Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> > --- > arch/arc/include/asm/ptrace.h | 3 +++ > arch/arc/kernel/signal.c | 12 ++++++++---- > 2 files changed, 11 insertions(+), 4 deletions(-) > > diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h > index 1711d56..8bf7ff4 100644 > --- a/arch/arc/include/asm/ptrace.h > +++ b/arch/arc/include/asm/ptrace.h > @@ -135,6 +135,9 @@ struct user_regs_struct { > #define in_syscall(regs) (regs->event & orig_r8_IS_SCALL) > #define in_brkpt_trap(regs) (regs->event & orig_r8_IS_BRKPT) > > +#define syscall_wont_restart(regs) (regs->event |= orig_r8_IS_SCALL_RESTARTED) > +#define syscall_restartable(regs) !(regs->event & orig_r8_IS_SCALL_RESTARTED) > + > #define current_pt_regs() \ > ({ \ > /* open-coded current_thread_info() */ \ > diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c > index 887a383..9a1ea2b 100644 > --- a/arch/arc/kernel/signal.c > +++ b/arch/arc/kernel/signal.c > @@ -131,6 +131,9 @@ SYSCALL_DEFINE0(rt_sigreturn) > if (restore_altstack(&sf->uc.uc_stack)) > goto badframe; > > + /* Don't restart from sigreturn */ > + syscall_wont_restart(regs); > + > return regs->r0; > > badframe: > @@ -321,13 +324,13 @@ void do_signal(struct pt_regs *regs) > > signr = get_signal_to_deliver(&info, &ka, regs, NULL); > > - /* Are we from a system call? */ > - restart_scall = in_syscall(regs); > + restart_scall = in_syscall(regs) && syscall_restartable(regs); > > if (signr > 0) { > - if (restart_scall) > + if (restart_scall) { > arc_restart_syscall(&ka, regs); > - > + syscall_wont_restart(regs); /* No more restarts */ > + } > handle_signal(signr, &ka, &info, regs); > return; > } > @@ -342,6 +345,7 @@ void do_signal(struct pt_regs *regs) > regs->r8 = __NR_restart_syscall; > regs->ret -= 4; > } > + syscall_wont_restart(regs); /* No more restarts */ > } > > /* If there's no signal to deliver, restore the saved sigmask back */ > If this looks OK, can I get your ACK on this. Thx, -Vineet -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
