| Message ID | 20160716080502.GA4700@Karyakshetra (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Please ignore this mail. I have already sent a patch for this driver Thanks, Bhaktipriya On Sat, Jul 16, 2016 at 1:35 PM, Bhaktipriya Shridhar <bhaktipriya96@gmail.com> wrote: > The workqueue has a single workitem(&ss->ws) and hence doesn't require > ordering. Also, it is not being used on a memory reclaim path. Hence, the > singlethreaded workqueue has been replaced with the use of system_wq. > > System workqueues have been able to handle high level of concurrency > for a long time now and hence it's not required to have a singlethreaded > workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue > created with create_singlethread_workqueue(), system_wq allows multiple > work items to overlap executions even on the same CPU; however, a > per-cpu workqueue doesn't have any CPU locality or global ordering > guarantee unless the target CPU is explicitly specified and thus the > increase of local concurrency shouldn't make any difference. > > Work item has been flushed in spi_sh_remove() to ensure that > there are no pending tasks while disconnecting the driver. > > Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com> > --- > drivers/spi/spi-sh.c | 16 +++------------- > 1 file changed, 3 insertions(+), 13 deletions(-) > > diff --git a/drivers/spi/spi-sh.c b/drivers/spi/spi-sh.c > index 5025011..2bf53f0 100644 > --- a/drivers/spi/spi-sh.c > +++ b/drivers/spi/spi-sh.c > @@ -82,7 +82,6 @@ struct spi_sh_data { > int irq; > struct spi_master *master; > struct list_head queue; > - struct workqueue_struct *workqueue; > struct work_struct ws; > unsigned long cr1; > wait_queue_head_t wait; > @@ -380,7 +379,7 @@ static int spi_sh_transfer(struct spi_device *spi, struct spi_message *mesg) > spi_sh_clear_bit(ss, SPI_SH_SSA, SPI_SH_CR1); > > list_add_tail(&mesg->queue, &ss->queue); > - queue_work(ss->workqueue, &ss->ws); > + schedule_work(&ss->ws); > > spin_unlock_irqrestore(&ss->lock, flags); > > @@ -425,7 +424,7 @@ static int spi_sh_remove(struct platform_device *pdev) > struct spi_sh_data *ss = platform_get_drvdata(pdev); > > spi_unregister_master(ss->master); > - destroy_workqueue(ss->workqueue); > + flush_work(&ss->ws); > free_irq(ss->irq, ss); > > return 0; > @@ -484,18 +483,11 @@ static int spi_sh_probe(struct platform_device *pdev) > spin_lock_init(&ss->lock); > INIT_WORK(&ss->ws, spi_sh_work); > init_waitqueue_head(&ss->wait); > - ss->workqueue = create_singlethread_workqueue( > - dev_name(master->dev.parent)); > - if (ss->workqueue == NULL) { > - dev_err(&pdev->dev, "create workqueue error\n"); > - ret = -EBUSY; > - goto error1; > - } > > ret = request_irq(irq, spi_sh_irq, 0, "spi_sh", ss); > if (ret < 0) { > dev_err(&pdev->dev, "request_irq error\n"); > - goto error2; > + goto error1; > } > > master->num_chipselect = 2; > @@ -514,8 +506,6 @@ static int spi_sh_probe(struct platform_device *pdev) > > error3: > free_irq(irq, ss); > - error2: > - destroy_workqueue(ss->workqueue); > error1: > spi_master_put(master); > > -- > 2.1.4 > -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/spi/spi-sh.c b/drivers/spi/spi-sh.c index 5025011..2bf53f0 100644 --- a/drivers/spi/spi-sh.c +++ b/drivers/spi/spi-sh.c @@ -82,7 +82,6 @@ struct spi_sh_data { int irq; struct spi_master *master; struct list_head queue; - struct workqueue_struct *workqueue; struct work_struct ws; unsigned long cr1; wait_queue_head_t wait; @@ -380,7 +379,7 @@ static int spi_sh_transfer(struct spi_device *spi, struct spi_message *mesg) spi_sh_clear_bit(ss, SPI_SH_SSA, SPI_SH_CR1); list_add_tail(&mesg->queue, &ss->queue); - queue_work(ss->workqueue, &ss->ws); + schedule_work(&ss->ws); spin_unlock_irqrestore(&ss->lock, flags); @@ -425,7 +424,7 @@ static int spi_sh_remove(struct platform_device *pdev) struct spi_sh_data *ss = platform_get_drvdata(pdev); spi_unregister_master(ss->master); - destroy_workqueue(ss->workqueue); + flush_work(&ss->ws); free_irq(ss->irq, ss); return 0; @@ -484,18 +483,11 @@ static int spi_sh_probe(struct platform_device *pdev) spin_lock_init(&ss->lock); INIT_WORK(&ss->ws, spi_sh_work); init_waitqueue_head(&ss->wait); - ss->workqueue = create_singlethread_workqueue( - dev_name(master->dev.parent)); - if (ss->workqueue == NULL) { - dev_err(&pdev->dev, "create workqueue error\n"); - ret = -EBUSY; - goto error1; - } ret = request_irq(irq, spi_sh_irq, 0, "spi_sh", ss); if (ret < 0) { dev_err(&pdev->dev, "request_irq error\n"); - goto error2; + goto error1; } master->num_chipselect = 2; @@ -514,8 +506,6 @@ static int spi_sh_probe(struct platform_device *pdev) error3: free_irq(irq, ss); - error2: - destroy_workqueue(ss->workqueue); error1: spi_master_put(master);
The workqueue has a single workitem(&ss->ws) and hence doesn't require ordering. Also, it is not being used on a memory reclaim path. Hence, the singlethreaded workqueue has been replaced with the use of system_wq. System workqueues have been able to handle high level of concurrency for a long time now and hence it's not required to have a singlethreaded workqueue just to gain concurrency. Unlike a dedicated per-cpu workqueue created with create_singlethread_workqueue(), system_wq allows multiple work items to overlap executions even on the same CPU; however, a per-cpu workqueue doesn't have any CPU locality or global ordering guarantee unless the target CPU is explicitly specified and thus the increase of local concurrency shouldn't make any difference. Work item has been flushed in spi_sh_remove() to ensure that there are no pending tasks while disconnecting the driver. Signed-off-by: Bhaktipriya Shridhar <bhaktipriya96@gmail.com> --- drivers/spi/spi-sh.c | 16 +++------------- 1 file changed, 3 insertions(+), 13 deletions(-) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html