linux-kernel - [PATCH] x86/kgdb: Replace bool_int_array[NR

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Date:	Sat, 26 Sep 2015 14:47:17 +0200
From:	Denys Vlasenko <dvlasenk@...hat.com>
To:	Jason Wessel <jason.wessel@...driver.com>,
	Ingo Molnar <mingo@...nel.org>
Cc:	Denys Vlasenko <dvlasenk@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] x86/kgdb: Replace bool_int_array[NR_CPUS] with bitmap

Straigntforward conversion from
    int was_in_debug_nmi[NR_CPUS]
to
    DECLARE_BITMAP(was_in_debug_nmi, NR_CPUS)

Saves about 2 kbytes in bss for NR_CPUS=512.

Signed-off-by: Denys Vlasenko <dvlasenk@...hat.com>
CC: Jason Wessel <jason.wessel@...driver.com>
CC: Ingo Molnar <mingo@...nel.org>
CC: H. Peter Anvin <hpa@...or.com>
CC: x86@...nel.org
CC: linux-kernel@...r.kernel.org
---
 arch/x86/kernel/kgdb.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/kgdb.c b/arch/x86/kernel/kgdb.c
index d6178d9..dd0a003 100644
--- a/arch/x86/kernel/kgdb.c
+++ b/arch/x86/kernel/kgdb.c
@@ -511,24 +511,27 @@ single_step_cont(struct pt_regs *regs, struct die_args *args)
 	return NOTIFY_STOP;
 }
 
-static int was_in_debug_nmi[NR_CPUS];
+static DECLARE_BITMAP(was_in_debug_nmi, NR_CPUS);
 
 static int kgdb_nmi_handler(unsigned int cmd, struct pt_regs *regs)
 {
+	int cpu;
+
 	switch (cmd) {
 	case NMI_LOCAL:
 		if (atomic_read(&kgdb_active) != -1) {
 			/* KGDB CPU roundup */
-			kgdb_nmicallback(raw_smp_processor_id(), regs);
-			was_in_debug_nmi[raw_smp_processor_id()] = 1;
+			cpu = raw_smp_processor_id();
+			kgdb_nmicallback(cpu, regs);
+			set_bit(cpu, was_in_debug_nmi);
 			touch_nmi_watchdog();
 			return NMI_HANDLED;
 		}
 		break;
 
 	case NMI_UNKNOWN:
-		if (was_in_debug_nmi[raw_smp_processor_id()]) {
-			was_in_debug_nmi[raw_smp_processor_id()] = 0;
+		cpu = raw_smp_processor_id();
+		if (__test_and_clear_bit(cpu, was_in_debug_nmi)) {
 			return NMI_HANDLED;
 		}
 		break;
-- 
1.8.1.4

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