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 <[email protected]>
---
arch/arm64/kernel/traps.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 0805b44..2e2ff88 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -274,10 +274,12 @@ static DEFINE_RAW_SPINLOCK(die_lock);
void die(const char *str, struct pt_regs *regs, int err)
{
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, regs);
@@ -287,13 +289,15 @@ 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);
}
--
2.7.4
Hi Maintainers,
Could you please help to take a look and give some comments? Thanks in advance.
Best Regards
Qiao
-----Original Message-----
From: Zhou Qiao
Sent: Friday, July 07, 2017 5:30 PM
To: [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]; [email protected]
Cc: Zhou Qiao
Subject: [PATCH V2] arm64: traps: disable irq in die()
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 <[email protected]>
---
arch/arm64/kernel/traps.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 0805b44..2e2ff88 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -274,10 +274,12 @@ static DEFINE_RAW_SPINLOCK(die_lock); void die(const char *str, struct pt_regs *regs, int err) {
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, regs);
@@ -287,13 +289,15 @@ 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);
}
--
2.7.4
On Fri, Jul 21, 2017 at 07:38:42AM +0000, Zhou Qiao(周侨) wrote:
> Could you please help to take a look and give some comments? Thanks in
> advance.
I've queued this on the arm64 for-next/fixes/core branch.
Will
On 2017年07月21日 16:32, Will Deacon wrote:
> On Fri, Jul 21, 2017 at 07:38:42AM +0000, Zhou Qiao(周侨) wrote:
>> Could you please help to take a look and give some comments? Thanks in
>> advance.
> I've queued this on the arm64 for-next/fixes/core branch.
Got it. Thanks!
>
> Will
Best Regards
Qiao