Commit 60b4c9d5 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Greg Kroah-Hartman
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usb/c67x00: Replace tasklet with work 



Tasklets have long been deprecated as being too heavy on the system
by running in irq context - and this is not a performance critical
path. If a higher priority process wants to run, it must wait for
the tasklet to finish before doing so.

c67x00_do_work() will now run in process context and have further
concurrency (tasklets being serialized among themselves), but this
is done holding the c67x00->lock, so it should be fine. Furthermore,
this patch fixes the usage of the lock in the callback as otherwise
it would need to be irq-safe.

Signed-off-by: default avatarDavidlohr Bueso <dbueso@suse.de>
Link: https://lore.kernel.org/r/20210113031537.79859-1-dave@stgolabs.net


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7cbcd008

drivers/usb/c67x00/c67x00-hcd.h

+1 −1
Original line number Diff line number Diff line
@@ -76,7 +76,7 @@ struct c67x00_hcd { 
	u16 next_td_addr;

	u16 next_buf_addr;



	struct tasklet_struct tasklet;

	struct work_struct work;



	struct completion endpoint_disable;

drivers/usb/c67x00/c67x00-sched.c

+7 −5
Original line number Diff line number Diff line
@@ -1123,24 +1123,26 @@ static void c67x00_do_work(struct c67x00_hcd *c67x00) 


/* -------------------------------------------------------------------------- */



static void c67x00_sched_tasklet(struct tasklet_struct *t)

static void c67x00_sched_work(struct work_struct *work)

{

	struct c67x00_hcd *c67x00 = from_tasklet(c67x00, t, tasklet);

	struct c67x00_hcd *c67x00;



	c67x00 = container_of(work, struct c67x00_hcd, work);

	c67x00_do_work(c67x00);

}



void c67x00_sched_kick(struct c67x00_hcd *c67x00)

{

	tasklet_hi_schedule(&c67x00->tasklet);

	queue_work(system_highpri_wq, &c67x00->work);

}



int c67x00_sched_start_scheduler(struct c67x00_hcd *c67x00)

{

	tasklet_setup(&c67x00->tasklet, c67x00_sched_tasklet);

	INIT_WORK(&c67x00->work, c67x00_sched_work);

	return 0;

}



void c67x00_sched_stop_scheduler(struct c67x00_hcd *c67x00)

{

	tasklet_kill(&c67x00->tasklet);

	cancel_work_sync(&c67x00->work);

}