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. A more suitable equivalent
is to converted to threaded irq instead and deal with the async
processing in task context.
Signed-off-by: Davidlohr Bueso <[email protected]>
---
drivers/block/umem.c | 23 ++++++++++-------------
1 file changed, 10 insertions(+), 13 deletions(-)
diff --git a/drivers/block/umem.c b/drivers/block/umem.c
index 982732dbe82e..6b0a110f9233 100644
--- a/drivers/block/umem.c
+++ b/drivers/block/umem.c
@@ -120,7 +120,6 @@ struct cardinfo {
int Active, Ready;
- struct tasklet_struct tasklet;
unsigned int dma_status;
struct {
@@ -243,7 +242,7 @@ static void dump_dmastat(struct cardinfo *card, unsigned int dmastat)
* overloaded to record whether it was a read or a write.
*
* The interrupt handler only polls the device to clear the interrupt.
- * The processing of the result is done in a tasklet.
+ * The processing of the result is done in threaded irq.
*/
static void mm_start_io(struct cardinfo *card)
@@ -405,7 +404,7 @@ static int add_bio(struct cardinfo *card)
return 1;
}
-static void process_page(unsigned long data)
+static irqreturn_t process_page(int irq, void *__card)
{
/* check if any of the requests in the page are DMA_COMPLETE,
* and deal with them appropriately.
@@ -415,10 +414,10 @@ static void process_page(unsigned long data)
*/
struct mm_page *page;
struct bio *return_bio = NULL;
- struct cardinfo *card = (struct cardinfo *)data;
+ struct cardinfo *card = (struct cardinfo *)__card;
unsigned int dma_status = card->dma_status;
- spin_lock(&card->lock);
+ spin_lock_bh(&card->lock);
if (card->Active < 0)
goto out_unlock;
page = &card->mm_pages[card->Active];
@@ -493,7 +492,7 @@ static void process_page(unsigned long data)
mm_start_io(card);
}
out_unlock:
- spin_unlock(&card->lock);
+ spin_unlock_bh(&card->lock);
while (return_bio) {
struct bio *bio = return_bio;
@@ -502,6 +501,8 @@ static void process_page(unsigned long data)
bio->bi_next = NULL;
bio_endio(bio);
}
+
+ return IRQ_HANDLED;
}
static void mm_unplug(struct blk_plug_cb *cb, bool from_schedule)
@@ -637,11 +638,10 @@ HW_TRACE(0x30);
/* and process the DMA descriptors */
card->dma_status = dma_status;
- tasklet_schedule(&card->tasklet);
HW_TRACE(0x36);
- return IRQ_HANDLED;
+ return IRQ_WAKE_THREAD;
}
/*
@@ -891,8 +891,6 @@ static int mm_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
if (!card->queue)
goto failed_alloc;
- tasklet_init(&card->tasklet, process_page, (unsigned long)card);
-
card->check_batteries = 0;
mem_present = readb(card->csr_remap + MEMCTRLSTATUS_MEMORY);
@@ -951,8 +949,8 @@ static int mm_pci_probe(struct pci_dev *dev, const struct pci_device_id *id)
data = ~data;
data += 1;
- if (request_irq(dev->irq, mm_interrupt, IRQF_SHARED, DRIVER_NAME,
- card)) {
+ if (request_threaded_irq(dev->irq, mm_interrupt, process_page,
+ IRQF_SHARED, DRIVER_NAME, card)) {
dev_printk(KERN_ERR, &card->dev->dev,
"Unable to allocate IRQ\n");
ret = -ENODEV;
@@ -1015,7 +1013,6 @@ static void mm_pci_remove(struct pci_dev *dev)
{
struct cardinfo *card = pci_get_drvdata(dev);
- tasklet_kill(&card->tasklet);
free_irq(dev->irq, card);
iounmap(card->csr_remap);
--
2.26.2
On Mon, Mar 22, 2021 at 05:48:56PM -0700, Davidlohr Bueso wrote:
> 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. A more suitable equivalent
> is to converted to threaded irq instead and deal with the async
> processing in task context.
I'm really curious if this driver is still in use at all, or if we
can drop it.
On Tue, 23 Mar 2021, Jens Axboe wrote:
>Me too, I'd be surprised if anyone has used it in... forever. We can
>probably drop it - I really dislike making core changes to something
>that can't even be tested. Davidlohr, assuming you had no way of
>testing this change?
No, no way of testing these changes - I got here via git grep.
On 3/23/21 11:24 AM, Christoph Hellwig wrote:
> On Mon, Mar 22, 2021 at 05:48:56PM -0700, Davidlohr Bueso wrote:
>> 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. A more suitable equivalent
>> is to converted to threaded irq instead and deal with the async
>> processing in task context.
>
> I'm really curious if this driver is still in use at all, or if we
> can drop it.
Me too, I'd be surprised if anyone has used it in... forever. We can
probably drop it - I really dislike making core changes to something
that can't even be tested. Davidlohr, assuming you had no way of
testing this change?
--
Jens Axboe