Messages in this thread Patch in this message | | | Date | Mon, 27 Nov 2023 21:25:58 +0100 (CET) | From | Richard Weinberger <> | Subject | Re: [PATCH] ubi: don't decrease ubi->ref_count on detach error |
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----- Ursprüngliche Mail ----- > Von: "Daniel Golle" <daniel@makrotopia.org> > An: "richard" <richard@nod.at>, "Miquel Raynal" <miquel.raynal@bootlin.com>, "Vignesh Raghavendra" <vigneshr@ti.com>, > "Artem Bityutskiy" <Artem.Bityutskiy@nokia.com>, "linux-mtd" <linux-mtd@lists.infradead.org>, "linux-kernel" > <linux-kernel@vger.kernel.org> > CC: "John Crispin" <john@phrozen.org> > Gesendet: Montag, 27. November 2023 18:09:14 > Betreff: [PATCH] ubi: don't decrease ubi->ref_count on detach error
> If attempting to detach a UBI device while it is still busy, detaching > is refused. However, the reference counter is still being decreased > despite the error. Rework detach function to only decrease the refcnt > once all conditions for detachment are met. > > Fixes: cdfa788acd13 ("UBI: prepare attach and detach functions") > Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Good catch! Did you find this by review or while testing?
> --- > drivers/mtd/ubi/build.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c > index 7d4ff1193db6f..f47987ee9a31b 100644 > --- a/drivers/mtd/ubi/build.c > +++ b/drivers/mtd/ubi/build.c > @@ -1099,16 +1099,16 @@ int ubi_detach_mtd_dev(int ubi_num, int anyway) > > spin_lock(&ubi_devices_lock); > put_device(&ubi->dev); > - ubi->ref_count -= 1; > - if (ubi->ref_count) { > + if (ubi->ref_count > 1) {
Is there a specific reason why you have modified the check to test only for ref_count being positive? If rec_counts turns negative, due to a bug, we could still stop it here.
> if (!anyway) { > spin_unlock(&ubi_devices_lock); > return -EBUSY; > } > /* This may only happen if there is a bug */ > ubi_err(ubi, "%s reference count %d, destroy anyway", > - ubi->ubi_name, ubi->ref_count); > + ubi->ubi_name, ubi->ref_count - 1); > } > + ubi->ref_count -= 1;
Please add there an ubi_asert() which tests whether ref_count is really zero. ...just to be more bullet proof.
Thanks, //richard
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