On Sat, Aug 20, 2022 at 08:14:42PM +0200, Greg Kroah-Hartman wrote: > On Fri, Aug 19, 2022 at 09:35:01PM +0200, Uwe Kleine-König wrote: > > Hello Greg, > > > > On Tue, Aug 16, 2022 at 12:40:50PM +0200, Greg Kroah-Hartman wrote: > > > On Mon, Aug 15, 2022 at 11:49:11PM +0200, Uwe Kleine-König wrote: > > > > On Mon, Aug 15, 2022 at 07:52:27PM +0200, Greg Kroah-Hartman wrote: > > > > > From: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> > > > > > > > > > > [ Upstream commit 7d4edccc9bbfe1dcdff641343f7b0c6763fbe774 ] > > > > > > > > > > Taking a lock at the beginning of .remove() doesn't prevent new readers. > > > > > With the existing approach it can happen, that a read occurs just when > > > > > the lock was taken blocking the reader until the lock is released at the > > > > > end of the remove callback which then accessed *data that is already > > > > > freed then. > > > > > > > > > > To actually fix this problem the hwmon core needs some adaption. Until > > > > > this is implemented take the optimistic approach of assuming that all > > > > > readers are gone after hwmon_device_unregister() and > > > > > sysfs_remove_group() as most other drivers do. (And once the core > > > > > implements that, taking the lock would deadlock.) > > > > > > > > > > So drop the lock, move the reset to after device unregistration to keep > > > > > the device in a workable state until it's deregistered. Also add a error > > > > > message in case the reset fails and return 0 anyhow. (Returning an error > > > > > code, doesn't stop the platform device unregistration and only results > > > > > in a little helpful error message before the devm cleanup handlers are > > > > > called.) > > > > > > > > > > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> > > > > > Link: https://lore.kernel.org/r/20220725194344.150098-1-u.kleine-koenig@xxxxxxxxxxxxxx > > > > > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> > > > > > Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > > > > > > > > Does this mean my concerns I expressed in the mail with Message-Id: > > > > 20220814155638.idxnihylofsxqlql@xxxxxxxxxxxxxx were not taken into > > > > consideration? > > > > > > I can't find that message-id on lore.kernel.org, do you have a link? > > > > Oh, I missed your request earlier. No I don't have a link, the mail was > > sent to Sasha Levin, Jean Delvare, Guenter Roeck and stable-commits as I > > just replied to the "note to let you know that I've just added the patch > > titled [...] to the 5.19-stable tree". > > Ok, I've dropped it now from all pending queues (5.10 and older), I can > also revert it from the newer ones if you want me to. Actually I don't care much. It touches a path that is not usually hit, because platform devices are not removed very often. So I expect even if the problem with this driver is a different one now, we won't get any regressions here. Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
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