arm64: traps: disable irq in die()

commit 6f44a0bacb79a03972c83759711832b382b1b8ac upstream.

In current die(), the irq is disabled for __die() handle, not
including the possible panic() handling. Since the log in __die()
can take several hundreds ms, new irq might come and interrupt
current die().

If the process calling die() holds some critical resource, and some
other process scheduled later also needs it, then it would deadlock.
The first panic will not be executed.

So here disable irq for the whole flow of die().

Signed-off-by: Qiao Zhou <qiaozhou@asrmicro.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 5963be2e05f0d0cc5b70a9eaf346e848edc81b65..28bef94cf7927350449ebb8b58f91dd309a5dd48 100644 (file)
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -266,10 +266,12 @@ void die(const char *str, struct pt_regs *regs, int err)
 {
        struct thread_info *thread = current_thread_info();
        int ret;
+       unsigned long flags;
+
+       raw_spin_lock_irqsave(&die_lock, flags);
 
        oops_enter();
 
-       raw_spin_lock_irq(&die_lock);
        console_verbose();
        bust_spinlocks(1);
        ret = __die(str, err, thread, regs);
@@ -279,13 +281,15 @@ void die(const char *str, struct pt_regs *regs, int err)
 
        bust_spinlocks(0);
        add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
-       raw_spin_unlock_irq(&die_lock);
        oops_exit();
 
        if (in_interrupt())
                panic("Fatal exception in interrupt");
        if (panic_on_oops)
                panic("Fatal exception");
+
+       raw_spin_unlock_irqrestore(&die_lock, flags);
+
        if (ret != NOTIFY_STOP)
                do_exit(SIGSEGV);
 }