Messages in this thread | | | Date | Wed, 10 Apr 2024 13:52:04 +0300 | Subject | Re: [PATCH v2 4/9] media: subdev: Fix use of sd->enabled_streams in call_s_stream() | From | Tomi Valkeinen <> |
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On 10/04/2024 13:05, Sakari Ailus wrote: > Moi, > > On Fri, Apr 05, 2024 at 12:14:22PM +0300, Tomi Valkeinen wrote: >> call_s_stream() uses sd->enabled_streams to track whether streaming has >> already been enabled. However, >> v4l2_subdev_enable/disable_streams_fallback(), which was the original >> user of this field, already uses it, and >> v4l2_subdev_enable/disable_streams_fallback() will call call_s_stream(). >> >> This leads to a conflict as both functions set the field. Afaics, both >> functions set the field to the same value, so it won't cause a runtime >> bug, but it's still wrong and if we, e.g., change how >> v4l2_subdev_enable/disable_streams_fallback() operates we might easily >> cause bugs. >> >> Fix this by adding a new field, 'streaming_enabled', for >> call_s_stream(). >> >> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> >> --- >> drivers/media/v4l2-core/v4l2-subdev.c | 8 ++------ >> include/media/v4l2-subdev.h | 3 +++ >> 2 files changed, 5 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c >> index a15a41576918..94483b238f2a 100644 >> --- a/drivers/media/v4l2-core/v4l2-subdev.c >> +++ b/drivers/media/v4l2-core/v4l2-subdev.c >> @@ -421,12 +421,8 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable) >> * The .s_stream() operation must never be called to start or stop an >> * already started or stopped subdev. Catch offenders but don't return >> * an error yet to avoid regressions. >> - * >> - * As .s_stream() is mutually exclusive with the .enable_streams() and >> - * .disable_streams() operation, we can use the enabled_streams field >> - * to store the subdev streaming state. >> */ >> - if (WARN_ON(!!sd->enabled_streams == !!enable)) >> + if (WARN_ON(!!sd->streaming_enabled == !!enable)) > > A single ! is enough on both sides.
Or perhaps (sd->streaming_enabled == !!enable).
> >> return 0; >> >> if (enable) >> @@ -442,7 +438,7 @@ static int call_s_stream(struct v4l2_subdev *sd, int enable) >> } >> >> if (!ret) >> - sd->enabled_streams = enable ? BIT(0) : 0; >> + sd->streaming_enabled = !!enable; > > No need for !! unless you think it needs to be very loud. Casting a > non-boolean value to boolean results in true if it's non-zero.
Indeed. My coding style for booleans seems to be from times long past.
Tomi
> >> >> return ret; >> } >> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h >> index a9e6b8146279..f55d03e0acc1 100644 >> --- a/include/media/v4l2-subdev.h >> +++ b/include/media/v4l2-subdev.h >> @@ -1043,6 +1043,8 @@ struct v4l2_subdev_platform_data { >> * v4l2_subdev_enable_streams() and >> * v4l2_subdev_disable_streams() helper functions for fallback >> * cases. >> + * @streaming_enabled: Tracks whether streaming has been enabled with s_stream. >> + * This is only for call_s_stream() internal use. >> * >> * Each instance of a subdev driver should create this struct, either >> * stand-alone or embedded in a larger struct. >> @@ -1091,6 +1093,7 @@ struct v4l2_subdev { >> */ >> struct v4l2_subdev_state *active_state; >> u64 enabled_streams; >> + bool streaming_enabled; >> }; >> >> >> >
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