| Message ID | 20250609-must_check-devm_mutex_init-v6-0-9540d5df9704@weissschuh.net |
|---|---|
| Headers | show |
| Series | locking/mutex: Mark devm_mutex_init() as __must_check | expand |
On 6/9/25 3:38 PM, Thomas Weißschuh wrote: > Even if it's not critical, the avoidance of checking the error code > from devm_mutex_init() call today diminishes the point of using devm > variant of it. Tomorrow it may even leak something. > > Add the missed check. > > Fixes: 87a59548af95 ("leds: lp8860: Use new mutex guards to cleanup function exits") > Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> > --- > drivers/leds/leds-lp8860.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/leds/leds-lp8860.c b/drivers/leds/leds-lp8860.c > index 52b97c9f2a03567aa12d4f63a951593a5e7017d5..0962c00c215a11f555a7878a3b65824b5219a1fa 100644 > --- a/drivers/leds/leds-lp8860.c > +++ b/drivers/leds/leds-lp8860.c > @@ -307,7 +307,9 @@ static int lp8860_probe(struct i2c_client *client) > led->client = client; > led->led_dev.brightness_set_blocking = lp8860_brightness_set; > > - devm_mutex_init(&client->dev, &led->lock); > + ret = devm_mutex_init(&client->dev, &led->lock); > + if (ret) > + return dev_err_probe(&client->dev, ret, "Failed to initialize lock\n"); I don't think the lock initialization can actually fail, if anything ever breaks it will be the devm allocation, which is a ENOMEM situation, so probably not worth printing anything. Either way is fine for __must_check sake so, Acked-by: Andrew Davis <afd@ti.com> > > led->regmap = devm_regmap_init_i2c(client, &lp8860_regmap_config); > if (IS_ERR(led->regmap)) { >
On Tue, Jun 10, 2025 at 12:57:37PM +0300, Andy Shevchenko wrote: > On Mon, Jun 09, 2025 at 09:59:46PM +0100, Mark Brown wrote: > > I don't understand the comment about leaking here? We might end up with > > an unitialised mutex but how would we leak anything? > In case if the mutex_init() allocates something that needs to be freed > (in the future). I don't see how checking the return value impacts that? The management via devm is still there either way.
On Tue, Jun 10, 2025 at 12:46:12PM +0100, Mark Brown wrote: > On Tue, Jun 10, 2025 at 12:57:37PM +0300, Andy Shevchenko wrote: > > On Mon, Jun 09, 2025 at 09:59:46PM +0100, Mark Brown wrote: > > > > I don't understand the comment about leaking here? We might end up with > > > an unitialised mutex but how would we leak anything? > > > In case if the mutex_init() allocates something that needs to be freed > > (in the future). > > I don't see how checking the return value impacts that? The management > via devm is still there either way. I see now what you mean. Yes, this is more likely applicable to non-devm case. Thomas, can you adjust the commit message(s), please, for v7?
devm_mutex_init() can fail. Make sure everybody checks the return value. All patches should go through the mutex tree together. It would be great if this could go in through a single tree at once. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> --- Changes in v6: - Rebase on v6.16-rc1 - Pick up review tag from Bartosz - Fix up spi-nxp-fspi - Fix up leds-lp8860 - Link to v5: https://lore.kernel.org/r/20250505-must_check-devm_mutex_init-v5-1-92fa4b793c6e@weissschuh.net Changes in v5: - Pick up review tag from Andy - Link to v4: https://lore.kernel.org/r/20250407-must_check-devm_mutex_init-v4-1-587bacc9f6b3@weissschuh.net Changes in v4: - Drop already applied leds-1202 driver patch - Rebase on v6.15-rc1 - Link to v3: https://lore.kernel.org/r/20250208-must_check-devm_mutex_init-v3-0-245e417dcc9e@weissschuh.net Changes in v3: - Introduce and use helper macro __mutex_init_ret() - Link to v2: https://lore.kernel.org/r/20250204-must_check-devm_mutex_init-v2-0-7b6271c4b7e6@weissschuh.net Changes in v2: - Rebase on 6.14-rc1 - Fix up leds-1202 driver - Link to v1: https://lore.kernel.org/r/20241202-must_check-devm_mutex_init-v1-1-e60eb97b8c72@weissschuh.net --- Thomas Weißschuh (3): spi: spi-nxp-fspi: check return value of devm_mutex_init() leds: lp8860: Check return value of devm_mutex_init() locking/mutex: Mark devm_mutex_init() as __must_check drivers/leds/leds-lp8860.c | 4 +++- drivers/spi/spi-nxp-fspi.c | 4 +++- include/linux/mutex.h | 11 +++++++---- 3 files changed, 13 insertions(+), 6 deletions(-) --- base-commit: 19272b37aa4f83ca52bdf9c16d5d81bdd1354494 change-id: 20241031-must_check-devm_mutex_init-cac583bda8fe Best regards,