linux-kernel - [PATCH 2/7] powerpc/traps: Return early in show_signal

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Message-Id: <20180724192720.32417-3-muriloo@linux.ibm.com>
Date:   Tue, 24 Jul 2018 16:27:15 -0300
From:   Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org
Cc:     "Alastair D'Silva" <alastair@...ilva.org>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Balbir Singh <bsingharora@...il.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Christophe Leroy <christophe.leroy@....fr>,
        Cyril Bur <cyrilbur@...il.com>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Michael Neuling <mikey@...ling.org>,
        Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Paul Mackerras <paulus@...ba.org>,
        Simon Guo <wei.guo.simon@...il.com>,
        Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>,
        "Tobin C . Harding" <me@...in.cc>, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 2/7] powerpc/traps: Return early in show_signal_msg()

Modify logic of show_signal_msg() to return early, if possible.  Replace
printk_ratelimited() by printk() and a default rate limit burst to limit
displaying unhandled signals messages.

Signed-off-by: Murilo Opsfelder Araujo <muriloo@...ux.ibm.com>
---
 arch/powerpc/kernel/traps.c | 21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index cbd3dc365193..4faab4705774 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -301,6 +301,13 @@ void user_single_step_siginfo(struct task_struct *tsk,
 	info->si_addr = (void __user *)regs->nip;
 }
 
+static bool show_unhandled_signals_ratelimited(void)
+{
+	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)
 {
@@ -309,11 +316,12 @@ static void show_signal_msg(int signr, struct pt_regs *regs, int code,
 	const char fmt64[] = KERN_INFO "%s[%d]: unhandled signal %d " \
 		"at %016lx nip %016lx lr %016lx code %x\n";
 
-	if (show_unhandled_signals && unhandled_signal(current, signr)) {
-		printk_ratelimited(regs->msr & MSR_64BIT ? fmt64 : fmt32,
-				   current->comm, current->pid, signr,
-				   addr, regs->nip, regs->link, code);
-	}
+	if (!unhandled_signal(current, signr))
+		return;
+
+	printk(regs->msr & MSR_64BIT ? fmt64 : fmt32,
+	       current->comm, current->pid, signr,
+	       addr, regs->nip, regs->link, code);
 }
 
 void _exception_pkey(int signr, struct pt_regs *regs, int code,
@@ -326,7 +334,8 @@ void _exception_pkey(int signr, struct pt_regs *regs, int code,
 		return;
 	}
 
-	show_signal_msg(signr, regs, code, addr);
+	if (show_unhandled_signals_ratelimited())
+		show_signal_msg(signr, regs, code, addr);
 
 	if (arch_irqs_disabled() && !arch_irq_disabled_regs(regs))
 		local_irq_enable();
-- 
2.17.1