[PATCH v2 3/9] crash_core: use panic_try_start() in crash_kexec()

[Jinchao Wang]

crash_kexec() had its own code to exclude parallel execution by setting
panic_cpu. This is already handled by panic_try_start(). Switch to
panic_try_start() to remove the duplication and keep the logic consistent.

Signed-off-by: Jinchao Wang <wangjinchao...@gmail.com>
---
 kernel/crash_core.c | 15 +++------------
 1 file changed, 3 insertions(+), 12 deletions(-)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index a4ef79591eb2..bb38bbaf3a26 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -4,6 +4,7 @@
  * Copyright (C) 2002-2004 Eric Biederman  <ebied...@xmission.com>
  */
 
+#include "linux/panic.h"
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/buildid.h>
@@ -143,17 +144,7 @@ STACK_FRAME_NON_STANDARD(__crash_kexec);
 
 __bpf_kfunc void crash_kexec(struct pt_regs *regs)
 {
-       int old_cpu, this_cpu;
-
-       /*
-        * Only one CPU is allowed to execute the crash_kexec() code as with
-        * panic().  Otherwise parallel calls of panic() and crash_kexec()
-        * may stop each other.  To exclude them, we use panic_cpu here too.
-        */
-       old_cpu = PANIC_CPU_INVALID;
-       this_cpu = raw_smp_processor_id();
-
-       if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) {
+       if (panic_try_start()) {
                /* This is the 1st CPU which comes here, so go ahead. */
                __crash_kexec(regs);
 
@@ -161,7 +152,7 @@ __bpf_kfunc void crash_kexec(struct pt_regs *regs)
                 * Reset panic_cpu to allow another panic()/crash_kexec()
                 * call.
                 */
-               atomic_set(&panic_cpu, PANIC_CPU_INVALID);
+               panic_reset();
        }
 }
 
-- 
2.43.0