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* atc260x has broken locking
@ 2022-02-23 11:07 Rolf Eike Beer
  2022-02-24 23:14 ` Cristian Ciocaltea
  0 siblings, 1 reply; 3+ messages in thread
From: Rolf Eike Beer @ 2022-02-23 11:07 UTC (permalink / raw)
  To: Manivannan Sadhasivam
  Cc: Cristian Ciocaltea, Lee Jones, linux-actions, linux-kernel

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When looking at this functions I found the locking to be broken for the atomic 
case (comments stripped):

static void regmap_lock_mutex(void *__mutex)
	struct mutex *mutex = __mutex;

	if (system_state > SYSTEM_RUNNING && irqs_disabled())

static void regmap_unlock_mutex(void *__mutex)
	struct mutex *mutex = __mutex;


When the mutex is already locked and the atomic context is hit then the lock 
will not be acquired, this is never noticed, and it afterwards is unlocked 

The comment says this is inspired from i2c_in_atomic_xfer_mode() to detect the 
atomic case, but the important caller __i2c_lock_bus_helper() actually does 
check and pass on the return value of mutex_trylock(), which is missing here.


Rolf Eike Beer, emlix GmbH,
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^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2022-02-25  7:37 UTC | newest]

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2022-02-23 11:07 atc260x has broken locking Rolf Eike Beer
2022-02-24 23:14 ` Cristian Ciocaltea
2022-02-25  7:36   ` Rolf Eike Beer

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