dmaengine: idxd: use spin_lock_irqsave before wait_event_lock_irq

In idxd_cmd_exec(), wait_event_lock_irq() explicitly calls
spin_unlock_irq()/spin_lock_irq(). If the interrupt is on before entering
wait_event_lock_irq(), it will become off status after
wait_event_lock_irq() is called. Later, wait_for_completion() may go to
sleep but irq is disabled. The scenario is warned in might_sleep().

Fix it by using spin_lock_irqsave() instead of the primitive spin_lock()
to save the irq status before entering wait_event_lock_irq() and using
spin_unlock_irqrestore() instead of the primitive spin_unlock() to restore
the irq status before entering wait_for_completion().

Before the change:
idxd_cmd_exec() {
interrupt is on
spin_lock()                        // interrupt is on
	wait_event_lock_irq()
		spin_unlock_irq()  // interrupt is enabled
		...
		spin_lock_irq()    // interrupt is disabled
spin_unlock()                      // interrupt is still disabled
wait_for_completion()              // report "BUG: sleeping function
				   // called from invalid context...
				   // in_atomic() irqs_disabled()"
}

After applying spin_lock_irqsave():
idxd_cmd_exec() {
interrupt is on
spin_lock_irqsave()                // save the on state
				   // interrupt is disabled
	wait_event_lock_irq()
		spin_unlock_irq()  // interrupt is enabled
		...
		spin_lock_irq()    // interrupt is disabled
spin_unlock_irqrestore()           // interrupt is restored to on
wait_for_completion()              // No Call trace
}

Fixes: f9f4082dbc56 ("dmaengine: idxd: remove interrupt disable for cmd_lock")
Signed-off-by: Rex Zhang <[email protected]>
Signed-off-by: Lijun Pan <[email protected]>
Reviewed-by: Dave Jiang <[email protected]>
Reviewed-by: Fenghua Yu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Vinod Koul <[email protected]>

0 files changed, 0 insertions, 0 deletions