panic: unset panic_on_warn inside panic()

commit 394e353ca9505293f1a9c59ce3a9f442c01ac441 upstream.

In the current code, the following three places need to unset
panic_on_warn before calling panic() to avoid recursive panics:

kernel/kcsan/report.c: print_report()
kernel/sched/core.c: __schedule_bug()
mm/kfence/report.c: kfence_report_error()

In order to avoid copy-pasting "panic_on_warn = 0" all over the places,
it is better to move it inside panic() and then remove it from the other
places.

Link: https://lkml.kernel.org/r/1644324666-15947-4-git-send-email-yangtiezhu@loongson.cn
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Xuefeng Li <lixuefeng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/panic.c b/kernel/panic.c
index f470a038b05bd1111bc3e0dd2195d6b15e823d14..5e2b764ff5d545edc02627d9b68edf4ab7b786af 100644 (file)
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -173,6 +173,16 @@ void panic(const char *fmt, ...)
        int old_cpu, this_cpu;
        bool _crash_kexec_post_notifiers = crash_kexec_post_notifiers;
 
+       if (panic_on_warn) {
+               /*
+                * This thread may hit another WARN() in the panic path.
+                * Resetting this prevents additional WARN() from panicking the
+                * system on this thread.  Other threads are blocked by the
+                * panic_mutex in panic().
+                */
+               panic_on_warn = 0;
+       }
+
        /*
         * Disable local interrupts. This will prevent panic_smp_self_stop
         * from deadlocking the first cpu that invokes the panic, since
@@ -571,16 +581,8 @@ void __warn(const char *file, int line, void *caller, unsigned taint,
        if (args)
                vprintk(args->fmt, args->args);
 
-       if (panic_on_warn) {
-               /*
-                * This thread may hit another WARN() in the panic path.
-                * Resetting this prevents additional WARN() from panicking the
-                * system on this thread.  Other threads are blocked by the
-                * panic_mutex in panic().
-                */
-               panic_on_warn = 0;
+       if (panic_on_warn)
                panic("panic_on_warn set ...\n");
-       }
 
        print_modules();