powerpc/traps: Avoid rate limit messages from show unhandled signals

mpe · mpe · commit 997dd26cb3c8 · 2018-08-20T20:19:46.000+10:00
In the recent commit to add an explicit ratelimit state when showing unhandled signals, commit 35a52a1 ("powerpc/traps: Use an explicit ratelimit state for show_signal_msg()"), I put the check of show_unhandled_signals and the ratelimit state before the call to unhandled_signal() so as to avoid unnecessarily calling the latter when show_unhandled_signals is false. However that causes us to check the ratelimit state on every call, so if we take a lot of *handled* signals that has the effect of making the ratelimit code print warnings that callbacks have been suppressed when they haven't. So rearrange the code so that we check show_unhandled_signals first, then call unhandled_signal() and finally check the ratelimit state. Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Murilo Opsfelder Araujo <muriloo@linux.ibm.com>
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
@@ -315,22 +315,21 @@ void user_single_step_siginfo(struct task_struct *tsk,
 	info->si_addr = (void __user *)regs->nip;
 }
 
-static bool show_unhandled_signals_ratelimited(void)
+static void show_signal_msg(int signr, struct pt_regs *regs, int code,
+			    unsigned long addr)
 {
 	static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL,
 				      DEFAULT_RATELIMIT_BURST);
-	return show_unhandled_signals && __ratelimit(&rs);
-}
 
-static void show_signal_msg(int signr, struct pt_regs *regs, int code,
-			    unsigned long addr)
-{
-	if (!show_unhandled_signals_ratelimited())
+	if (!show_unhandled_signals)
 		return;
 
 	if (!unhandled_signal(current, signr))
 		return;
 
+	if (!__ratelimit(&rs))
+		return;
+
 	pr_info("%s[%d]: %s (%d) at %lx nip %lx lr %lx code %x",
 		current->comm, current->pid, signame(signr), signr,
 		addr, regs->nip, regs->link, code);
