firewire: ohci: Use tasklet_disable_in_atomic() where required

tasklet_disable() is invoked in several places. Some of them are in atomic
context which prevents a conversion of tasklet_disable() to a sleepable
function.

The atomic callchains are:

 ar_context_tasklet()
   ohci_cancel_packet()
     tasklet_disable()

 ...
   ohci_flush_iso_completions()
     tasklet_disable()

The invocation of tasklet_disable() from at_context_flush() is always in
preemptible context.

Use tasklet_disable_in_atomic() for the two invocations in
ohci_cancel_packet() and ohci_flush_iso_completions().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210309084242.616379058@linutronix.de

drivers/firewire/ohci.c

@@ -2545,7 +2545,7 @@ static int ohci_cancel_packet(struct fw_card *card, struct fw_packet *packet)
 	struct driver_data *driver_data = packet->driver_data;
 	int ret = -ENOENT;
 
-	tasklet_disable(&ctx->tasklet);
+	tasklet_disable_in_atomic(&ctx->tasklet);
 
 	if (packet->ack != 0)
 		goto out;
@@ -3465,7 +3465,7 @@ static int ohci_flush_iso_completions(struct fw_iso_context *base)
 	struct iso_context *ctx = container_of(base, struct iso_context, base);
 	int ret = 0;
 
-	tasklet_disable(&ctx->context.tasklet);
+	tasklet_disable_in_atomic(&ctx->context.tasklet);
 
 	if (!test_and_set_bit_lock(0, &ctx->flushing_completions)) {
 		context_tasklet((unsigned long)&ctx->context);