On 4/6/24 4:09 AM, Dan Carpenter wrote:
On Fri, Apr 05, 2024 at 02:22:05PM -0700, Jackson Chui wrote:On Thu, Apr 04, 2024 at 05:05:09PM -0500, Alex Elder wrote:On 4/3/24 7:16 PM, Jackson Chui wrote:Reported by checkpatch: CHECK: Macro argument 'gcam' may be better as '(gcam)' to avoid precedence issuesI agree with your argument about the way the macro should be defined. But perhaps these gcam_*() functions could just be eliminated? I see 15 calls to gcam_err(), 1 call to gcam_dbg(), and none to gcam_info(). It would be a different patch, but maybe you could do that instead? -AlexDisambiguates '&' (address-of) operator and '->' operator precedence, accounting for how '(gcam)->bundle->dev' is a 'struct device' and not a 'struct device*', which is required by the dev_{dbg,info,err} driver model diagnostic macros. Issue found by checkpatch. Signed-off-by: Jackson Chui <jacksonchui.qwerty@xxxxxxxxx> --- drivers/staging/greybus/camera.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/staging/greybus/camera.c b/drivers/staging/greybus/camera.c index a8173aa3a995..d82a2d2abdca 100644 --- a/drivers/staging/greybus/camera.c +++ b/drivers/staging/greybus/camera.c @@ -180,9 +180,9 @@ static const struct gb_camera_fmt_info *gb_camera_get_format_info(u16 gb_fmt) #define GB_CAMERA_MAX_SETTINGS_SIZE 8192 -#define gcam_dbg(gcam, format...) dev_dbg(&gcam->bundle->dev, format) -#define gcam_info(gcam, format...) dev_info(&gcam->bundle->dev, format) -#define gcam_err(gcam, format...) dev_err(&gcam->bundle->dev, format) +#define gcam_dbg(gcam, format...) dev_dbg(&((gcam)->bundle->dev), format) +#define gcam_info(gcam, format...) dev_info(&((gcam)->bundle->dev), format) +#define gcam_err(gcam, format...) dev_err(&((gcam)->bundle->dev), format) static int gb_camera_operation_sync_flags(struct gb_connection *connection, int type, unsigned int flags,Thanks for the feedback, Alex! I thought about refactoring it, but I feel it is worth keeping the macro around. It acts as an apdater between callers, who have 'gcam' and want to log and what the dynamic debug macros expect. Without it, the code gets pretty ugly.Another idea would be to create a function: struct device *gcam_dev(struct gb_camera *gcam) { return &gcam->bundle->dev; } dev_dbg(gcam_dev(gcam), "received metadata ... (I don't know how to actually compile this code so I haven't tried it).
Yes, I prefer this over the original suggestion. But even here the gcam_dev() function doesn't add all that much value; it saves four characters I guess. Jackson, the basic principle that makes me say I don't like the wrapper macros is that the wrapper obscures the simple call(s) to dev_dbg(), etc. If there was something you wanted to do every time--along with calling dev_dbg()--then maybe the wrapper would be helpful, but instead it simply hides the standard call. Better to have the code just use the functions kernel programmers recognize. -Alex
regards, dan carpenter
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