* [PATCH] dm: remove pointless comparison @ 2014-01-07 3:53 Mikulas Patocka 2014-01-07 10:39 ` Joe Thornber 0 siblings, 1 reply; 5+ messages in thread From: Mikulas Patocka @ 2014-01-07 3:53 UTC (permalink / raw) To: Mike Snitzer, Alasdair G. Kergon; +Cc: dm-devel Remove pointless comparison in dm_get_from_kobject. The comparison is always true and the compiler optimizes it out anyway. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> --- drivers/md/dm.c | 2 -- 1 file changed, 2 deletions(-) Index: linux-3.13-rc7/drivers/md/dm.c =================================================================== --- linux-3.13-rc7.orig/drivers/md/dm.c 2014-01-07 01:28:27.000000000 +0100 +++ linux-3.13-rc7/drivers/md/dm.c 2014-01-07 01:28:39.000000000 +0100 @@ -2922,8 +2922,6 @@ struct mapped_device *dm_get_from_kobjec struct mapped_device *md; md = container_of(kobj, struct mapped_device, kobj); - if (&md->kobj != kobj) - return NULL; if (test_bit(DMF_FREEING, &md->flags) || dm_deleting_md(md)) ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] dm: remove pointless comparison 2014-01-07 3:53 [PATCH] dm: remove pointless comparison Mikulas Patocka @ 2014-01-07 10:39 ` Joe Thornber 2014-01-07 15:52 ` Mike Snitzer 0 siblings, 1 reply; 5+ messages in thread From: Joe Thornber @ 2014-01-07 10:39 UTC (permalink / raw) To: device-mapper development; +Cc: Mike Snitzer, Alasdair G. Kergon On Mon, Jan 06, 2014 at 10:53:28PM -0500, Mikulas Patocka wrote: > Remove pointless comparison in dm_get_from_kobject. The comparison is > always true and the compiler optimizes it out anyway. > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > > --- > drivers/md/dm.c | 2 -- > 1 file changed, 2 deletions(-) > > Index: linux-3.13-rc7/drivers/md/dm.c > =================================================================== > --- linux-3.13-rc7.orig/drivers/md/dm.c 2014-01-07 01:28:27.000000000 +0100 > +++ linux-3.13-rc7/drivers/md/dm.c 2014-01-07 01:28:39.000000000 +0100 > @@ -2922,8 +2922,6 @@ struct mapped_device *dm_get_from_kobjec > struct mapped_device *md; > > md = container_of(kobj, struct mapped_device, kobj); > - if (&md->kobj != kobj) > - return NULL; What were they trying to check? The compiler? ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: dm: remove pointless comparison 2014-01-07 10:39 ` Joe Thornber @ 2014-01-07 15:52 ` Mike Snitzer 2014-01-07 17:28 ` Milan Broz 0 siblings, 1 reply; 5+ messages in thread From: Mike Snitzer @ 2014-01-07 15:52 UTC (permalink / raw) To: device-mapper development, Alasdair G. Kergon; +Cc: ejt, Mikulas Patocka On Tue, Jan 07 2014 at 5:39am -0500, Joe Thornber <thornber@redhat.com> wrote: > On Mon, Jan 06, 2014 at 10:53:28PM -0500, Mikulas Patocka wrote: > > Remove pointless comparison in dm_get_from_kobject. The comparison is > > always true and the compiler optimizes it out anyway. > > > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > > > > --- > > drivers/md/dm.c | 2 -- > > 1 file changed, 2 deletions(-) > > > > Index: linux-3.13-rc7/drivers/md/dm.c > > =================================================================== > > --- linux-3.13-rc7.orig/drivers/md/dm.c 2014-01-07 01:28:27.000000000 +0100 > > +++ linux-3.13-rc7/drivers/md/dm.c 2014-01-07 01:28:39.000000000 +0100 > > @@ -2922,8 +2922,6 @@ struct mapped_device *dm_get_from_kobjec > > struct mapped_device *md; > > > > md = container_of(kobj, struct mapped_device, kobj); > > - if (&md->kobj != kobj) > > - return NULL; > > What were they trying to check? The compiler? > Milan's commit 784aae735d, and the current dm.c code, offers this comment above dm_get_from_kobject: /* * struct mapped_device should not be exported outside of dm.c * so use this check to verify that kobj is part of md structure */ I'm lacking the vision to _know_ why the kobject would suddenly be outside of the mapped_device without us knowing via code change.. The check does seem overly cautious/useless (if we remove it the above comment should be removed too). ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: dm: remove pointless comparison 2014-01-07 15:52 ` Mike Snitzer @ 2014-01-07 17:28 ` Milan Broz 2014-01-07 18:17 ` Mike Snitzer 0 siblings, 1 reply; 5+ messages in thread From: Milan Broz @ 2014-01-07 17:28 UTC (permalink / raw) To: device-mapper development Cc: ejt, Mikulas Patocka, Alasdair G. Kergon, Mike Snitzer On 01/07/2014 04:52 PM, Mike Snitzer wrote: > On Tue, Jan 07 2014 at 5:39am -0500, > Joe Thornber <thornber@redhat.com> wrote: > >> On Mon, Jan 06, 2014 at 10:53:28PM -0500, Mikulas Patocka wrote: >>> Remove pointless comparison in dm_get_from_kobject. The comparison is >>> always true and the compiler optimizes it out anyway. >>>gmane.linux.kernel.device-mapper.devel >>> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> >>> >>> --- >>> drivers/md/dm.c | 2 -- >>> 1 file changed, 2 deletions(-) >>> >>> Index: linux-3.13-rc7/drivers/md/dm.c >>> =================================================================== >>> --- linux-3.13-rc7.orig/drivers/md/dm.c 2014-01-07 01:28:27.000000000 +0100 >>> +++ linux-3.13-rc7/drivers/md/dm.c 2014-01-07 01:28:39.000000000 +0100 >>> @@ -2922,8 +2922,6 @@ struct mapped_device *dm_get_from_kobjec >>> struct mapped_device *md; >>> >>> md = container_of(kobj, struct mapped_device, kobj); >>> - if (&md->kobj != kobj) >>> - return NULL; >> >> What were they trying to check? The compiler? >> > > Milan's commit 784aae735d, and the current dm.c code, offers this > comment above dm_get_from_kobject: > > /* > * struct mapped_device should not be exported outside of dm.c > * so use this check to verify that kobj is part of md structure > */ > > I'm lacking the vision to _know_ why the kobject would suddenly be > outside of the mapped_device without us knowing via code change.. > > The check does seem overly cautious/useless (if we remove it the above > comment should be removed too). Yes, please remove both :) The check doesn't make sense. I think it is just relict of some experiments before I committed this simple embedded sysfs kobj handling (there were always problems like the missing .release function you are just solving in other thread). Milan ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: dm: remove pointless comparison 2014-01-07 17:28 ` Milan Broz @ 2014-01-07 18:17 ` Mike Snitzer 0 siblings, 0 replies; 5+ messages in thread From: Mike Snitzer @ 2014-01-07 18:17 UTC (permalink / raw) To: Milan Broz Cc: device-mapper development, Mikulas Patocka, ejt, Alasdair G. Kergon On Tue, Jan 07 2014 at 12:28pm -0500, Milan Broz <gmazyland@gmail.com> wrote: > On 01/07/2014 04:52 PM, Mike Snitzer wrote: > > On Tue, Jan 07 2014 at 5:39am -0500, > > Joe Thornber <thornber@redhat.com> wrote: > > > >> On Mon, Jan 06, 2014 at 10:53:28PM -0500, Mikulas Patocka wrote: > >>> Remove pointless comparison in dm_get_from_kobject. The comparison is > >>> always true and the compiler optimizes it out anyway. > >>>gmane.linux.kernel.device-mapper.devel > >>> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > >>> > >>> --- > >>> drivers/md/dm.c | 2 -- > >>> 1 file changed, 2 deletions(-) > >>> > >>> Index: linux-3.13-rc7/drivers/md/dm.c > >>> =================================================================== > >>> --- linux-3.13-rc7.orig/drivers/md/dm.c 2014-01-07 01:28:27.000000000 +0100 > >>> +++ linux-3.13-rc7/drivers/md/dm.c 2014-01-07 01:28:39.000000000 +0100 > >>> @@ -2922,8 +2922,6 @@ struct mapped_device *dm_get_from_kobjec > >>> struct mapped_device *md; > >>> > >>> md = container_of(kobj, struct mapped_device, kobj); > >>> - if (&md->kobj != kobj) > >>> - return NULL; > >> > >> What were they trying to check? The compiler? > >> > > > > Milan's commit 784aae735d, and the current dm.c code, offers this > > comment above dm_get_from_kobject: > > > > /* > > * struct mapped_device should not be exported outside of dm.c > > * so use this check to verify that kobj is part of md structure > > */ > > > > I'm lacking the vision to _know_ why the kobject would suddenly be > > outside of the mapped_device without us knowing via code change.. > > > > The check does seem overly cautious/useless (if we remove it the above > > comment should be removed too). > > Yes, please remove both :) The check doesn't make sense. Ok, I'll take that as your Acked-by, thanks. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2014-01-07 18:17 UTC | newest] Thread overview: 5+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2014-01-07 3:53 [PATCH] dm: remove pointless comparison Mikulas Patocka 2014-01-07 10:39 ` Joe Thornber 2014-01-07 15:52 ` Mike Snitzer 2014-01-07 17:28 ` Milan Broz 2014-01-07 18:17 ` Mike Snitzer
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