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gpu: nvgpu: fix race between do_idle() and unrailgate()

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While we are executing do_idle() API, it is possible that
unrailgate() gets invoked in midst of idling the GPU and
this can result in failure of do_idle()

To prevent simultaneous execution of these methods,
add a mutex railgate_lock and acquire it during
do_idle() and unrailgate() APIs

Also, keep this lock held if do_idle() is successful.
In success, lock will be released in do_unidle(),
otherwise release this lock before returning

Note that this lock should not be held in railgate() API
since we do not want it to be blocked during do_idle()

bug 1529160

Change-Id: I87114b5367eaa217376455a2699c0d21c451c889
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/434190
(cherry picked from commit 561dc8e0933ff2d72573292968b893a52f5f783a)
Reviewed-on: http://git-master/r/435131
Reviewed-by: Arto Merilainen <amerilainen@nvidia.com>
Reviewed-by: Sachin Nikam <snikam@nvidia.com>
This commit is contained in:
Deepak Nibade
2014-07-03 17:59:39 +05:30
committed by Dan Willemsen
parent d608aa53ee
commit 0b1f9e4272
2 changed files with 21 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
drivers/gpu/nvgpu/gk20a/gk20a.c
View File

@@ -1281,8 +1281,13 @@ static int _gk20a_pm_unrailgate(struct platform_device *pdev)
{ {
struct gk20a_platform *platform = platform_get_drvdata(pdev); struct gk20a_platform *platform = platform_get_drvdata(pdev);
int ret = 0; int ret = 0;
if (platform->unrailgate)
if (platform->unrailgate) {
mutex_lock(&platform->railgate_lock);
ret = platform->unrailgate(pdev); ret = platform->unrailgate(pdev);
mutex_unlock(&platform->railgate_lock);
}
return ret; return ret;
} }
@@ -1362,6 +1367,8 @@ static int gk20a_pm_init(struct platform_device *dev)
gk20a_dbg_fn(""); gk20a_dbg_fn("");
mutex_init(&platform->railgate_lock);
/* Initialise pm runtime */ /* Initialise pm runtime */
if (platform->clockgate_delay) { if (platform->clockgate_delay) {
pm_runtime_set_autosuspend_delay(&dev->dev, pm_runtime_set_autosuspend_delay(&dev->dev,
@@ -1739,6 +1746,13 @@ int gk20a_do_idle(void)
/* acquire busy lock to block other busy() calls */ /* acquire busy lock to block other busy() calls */
down_write(&g->busy_lock); down_write(&g->busy_lock);
/* acquire railgate lock to prevent unrailgate in midst of do_idle() */
mutex_lock(&platform->railgate_lock);
/* check if it is already railgated ? */
if (platform->is_railgated(pdev))
return 0;
/* prevent suspend by incrementing usage counter */ /* prevent suspend by incrementing usage counter */
pm_runtime_get_noresume(&pdev->dev); pm_runtime_get_noresume(&pdev->dev);
@@ -1776,11 +1790,12 @@ int gk20a_do_idle(void)
} }
/* GPU is not rail gated by now, return error */ /* GPU is not rail gated by now, return error */
up_write(&g->busy_lock); goto fail_timeout;
return -EBUSY;
fail: fail:
pm_runtime_put_noidle(&pdev->dev); pm_runtime_put_noidle(&pdev->dev);
fail_timeout:
mutex_unlock(&platform->railgate_lock);
up_write(&g->busy_lock); up_write(&g->busy_lock);
return -EBUSY; return -EBUSY;
} }
@@ -1794,8 +1809,10 @@ int gk20a_do_unidle(void)
bus_find_device_by_name(&platform_bus_type, bus_find_device_by_name(&platform_bus_type,
NULL, "gk20a.0")); NULL, "gk20a.0"));
struct gk20a *g = get_gk20a(pdev); struct gk20a *g = get_gk20a(pdev);
struct gk20a_platform *platform = dev_get_drvdata(&pdev->dev);
/* release the lock and open up all other busy() calls */ /* release the lock and open up all other busy() calls */
mutex_unlock(&platform->railgate_lock);
up_write(&g->busy_lock); up_write(&g->busy_lock);
return 0; return 0;

1
drivers/gpu/nvgpu/gk20a/platform_gk20a.h
View File

@@ -118,6 +118,7 @@ struct gk20a_platform {
/* Called to turn on the device */ /* Called to turn on the device */
int (*unrailgate)(struct platform_device *dev); int (*unrailgate)(struct platform_device *dev);
struct mutex railgate_lock;
/* Called to check state of device */ /* Called to check state of device */
bool (*is_railgated)(struct platform_device *dev); bool (*is_railgated)(struct platform_device *dev);