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SubjectRe: [PATCH] devcoredump: avoid -Wempty-body warnings
On Mon, Mar 22, 2021 at 11:19:53AM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> Cleaning out the last -Wempty-body warnings found some interesting
> cases with empty macros, along with harmless warnings like this one:
>
> drivers/base/devcoredump.c: In function 'dev_coredumpm':
> drivers/base/devcoredump.c:297:56: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
> 297 | /* nothing - symlink will be missing */;
> | ^
> drivers/base/devcoredump.c:301:56: error: suggest braces around empty body in an 'if' statement [-Werror=empty-body]
> 301 | /* nothing - symlink will be missing */;
> | ^
>
> Randy tried addressing this one before, and there were multiple
> other ideas in that thread.
>
> Pick up the one that Matthew Wilcox suggested by adding a
> WARN_ON_ONCE() and a comment.
>
> Link: https://lore.kernel.org/lkml/20200418184111.13401-8-rdunlap@infradead.org/
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Cc: Matthew Wilcox <willy@infradead.org>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
> drivers/base/devcoredump.c | 15 +++++++++------
> 1 file changed, 9 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/base/devcoredump.c b/drivers/base/devcoredump.c
> index 9243468e2c99..88e0d931439e 100644
> --- a/drivers/base/devcoredump.c
> +++ b/drivers/base/devcoredump.c
> @@ -292,13 +292,16 @@ void dev_coredumpm(struct device *dev, struct module *owner,
> if (device_add(&devcd->devcd_dev))
> goto put_device;
>
> - if (sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
> - "failing_device"))
> - /* nothing - symlink will be missing */;
> + /*
> + * These should normally not fail, but there is no problem
> + * continuing without the links, so just warn instead of
> + * failing.
> + */
> + WARN_ON_ONCE(sysfs_create_link(&devcd->devcd_dev.kobj, &dev->kobj,
> + "failing_device"));
>
> - if (sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
> - "devcoredump"))
> - /* nothing - symlink will be missing */;
> + WARN_ON_ONCE(sysfs_create_link(&dev->kobj, &devcd->devcd_dev.kobj,
> + "devcoredump"));

We do not want to reboot machines that have panic-on-warn set, so if
this really needs a trace dump, please do that instead...

thanks,

greg k-h

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