| Message ID | 20200603144949.1122421-7-a.darwish@linutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | seqlock: seqcount_t call sites bugfixes | expand |
On Wed, Jun 03, 2020 at 04:49:49PM +0200, Ahmed S. Darwish wrote: > Commit 3c3b177a9369 ("reservation: add support for read-only access > using rcu") introduced a sequence counter to manage updates to > reservations. Back then, the reservation object initializer > reservation_object_init() was always inlined. > > Having the sequence counter initialization inlined meant that each of > the call sites would have a different lockdep class key, which would've > broken lockdep's deadlock detection. The aforementioned commit thus > introduced, and exported, a custom seqcount lockdep class key and name. > > The commit 8735f16803f00 ("dma-buf: cleanup reservation_object_init...") > transformed the reservation object initializer to a normal non-inlined C > function. seqcount_init(), which automatically defines the seqcount > lockdep class key and must be called non-inlined, can now be safely used. > > Remove the seqcount custom lockdep class key, name, and export. Use > seqcount_init() inside the dma reservation object initializer. > > Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> > Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Patch lgtm, and Ahmed says plan is that this should land through -tip since it's part of a larger series, so Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> for merging through whatever tree/branch fits bets. I don't expect conflicts here, nothing in-flight touching this. I expect this will show up in 5.9-rc1 or so. Cheers, Daniel > --- > drivers/dma-buf/dma-resv.c | 9 +-------- > include/linux/dma-resv.h | 2 -- > 2 files changed, 1 insertion(+), 10 deletions(-) > > diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c > index 4264e64788c4..590ce7ad60a0 100644 > --- a/drivers/dma-buf/dma-resv.c > +++ b/drivers/dma-buf/dma-resv.c > @@ -50,12 +50,6 @@ > DEFINE_WD_CLASS(reservation_ww_class); > EXPORT_SYMBOL(reservation_ww_class); > > -struct lock_class_key reservation_seqcount_class; > -EXPORT_SYMBOL(reservation_seqcount_class); > - > -const char reservation_seqcount_string[] = "reservation_seqcount"; > -EXPORT_SYMBOL(reservation_seqcount_string); > - > /** > * dma_resv_list_alloc - allocate fence list > * @shared_max: number of fences we need space for > @@ -134,9 +128,8 @@ subsys_initcall(dma_resv_lockdep); > void dma_resv_init(struct dma_resv *obj) > { > ww_mutex_init(&obj->lock, &reservation_ww_class); > + seqcount_init(&obj->seq); > > - __seqcount_init(&obj->seq, reservation_seqcount_string, > - &reservation_seqcount_class); > RCU_INIT_POINTER(obj->fence, NULL); > RCU_INIT_POINTER(obj->fence_excl, NULL); > } > diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h > index ee50d10f052b..a6538ae7d93f 100644 > --- a/include/linux/dma-resv.h > +++ b/include/linux/dma-resv.h > @@ -46,8 +46,6 @@ > #include <linux/rcupdate.h> > > extern struct ww_class reservation_ww_class; > -extern struct lock_class_key reservation_seqcount_class; > -extern const char reservation_seqcount_string[]; > > /** > * struct dma_resv_list - a list of shared fences > -- > 2.20.1 >
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index 4264e64788c4..590ce7ad60a0 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -50,12 +50,6 @@ DEFINE_WD_CLASS(reservation_ww_class); EXPORT_SYMBOL(reservation_ww_class); -struct lock_class_key reservation_seqcount_class; -EXPORT_SYMBOL(reservation_seqcount_class); - -const char reservation_seqcount_string[] = "reservation_seqcount"; -EXPORT_SYMBOL(reservation_seqcount_string); - /** * dma_resv_list_alloc - allocate fence list * @shared_max: number of fences we need space for @@ -134,9 +128,8 @@ subsys_initcall(dma_resv_lockdep); void dma_resv_init(struct dma_resv *obj) { ww_mutex_init(&obj->lock, &reservation_ww_class); + seqcount_init(&obj->seq); - __seqcount_init(&obj->seq, reservation_seqcount_string, - &reservation_seqcount_class); RCU_INIT_POINTER(obj->fence, NULL); RCU_INIT_POINTER(obj->fence_excl, NULL); } diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h index ee50d10f052b..a6538ae7d93f 100644 --- a/include/linux/dma-resv.h +++ b/include/linux/dma-resv.h @@ -46,8 +46,6 @@ #include <linux/rcupdate.h> extern struct ww_class reservation_ww_class; -extern struct lock_class_key reservation_seqcount_class; -extern const char reservation_seqcount_string[]; /** * struct dma_resv_list - a list of shared fences
Commit 3c3b177a9369 ("reservation: add support for read-only access using rcu") introduced a sequence counter to manage updates to reservations. Back then, the reservation object initializer reservation_object_init() was always inlined. Having the sequence counter initialization inlined meant that each of the call sites would have a different lockdep class key, which would've broken lockdep's deadlock detection. The aforementioned commit thus introduced, and exported, a custom seqcount lockdep class key and name. The commit 8735f16803f00 ("dma-buf: cleanup reservation_object_init...") transformed the reservation object initializer to a normal non-inlined C function. seqcount_init(), which automatically defines the seqcount lockdep class key and must be called non-inlined, can now be safely used. Remove the seqcount custom lockdep class key, name, and export. Use seqcount_init() inside the dma reservation object initializer. Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- drivers/dma-buf/dma-resv.c | 9 +-------- include/linux/dma-resv.h | 2 -- 2 files changed, 1 insertion(+), 10 deletions(-)