[PATCH] ALSA: firewire-lib: Fix 'amdtp_domain_start()' when no AMDTP_OUT_STREAM stream is found
The intent here is to return an error code if we don't find what we are looking for in the 'list_for_each_entry()' loop.
's' is not NULL if the list is empty or if we scan the complete list. Introduce a new 'found' variable to handle such cases.
Fixes: 60dd49298ec5 ("ALSA: firewire-lib: handle several AMDTP streams in callback handler of IRQ target") Signed-off-by: Christophe JAILLET christophe.jaillet@wanadoo.fr --- We could test with" if (list_entry_is_head(s, &d->streams, list))" instead, but I find it much less readable. --- sound/firewire/amdtp-stream.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index aad9778d1c4d..9be2260e4ca2 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -1943,6 +1943,7 @@ int amdtp_domain_start(struct amdtp_domain *d, unsigned int tx_init_skip_cycles, unsigned int events_per_period = d->events_per_period; unsigned int queue_size; struct amdtp_stream *s; + bool found = false; int err;
if (replay_seq) { @@ -1955,10 +1956,12 @@ int amdtp_domain_start(struct amdtp_domain *d, unsigned int tx_init_skip_cycles,
// Select an IT context as IRQ target. list_for_each_entry(s, &d->streams, list) { - if (s->direction == AMDTP_OUT_STREAM) + if (s->direction == AMDTP_OUT_STREAM) { + found = true; break; + } } - if (!s) + if (!found) return -ENXIO; d->irq_target = s;
Hi,
On Thu, Jun 24, 2021 at 08:49:36PM +0200, Christophe JAILLET wrote:
The intent here is to return an error code if we don't find what we are looking for in the 'list_for_each_entry()' loop.
's' is not NULL if the list is empty or if we scan the complete list. Introduce a new 'found' variable to handle such cases.
Fixes: 60dd49298ec5 ("ALSA: firewire-lib: handle several AMDTP streams in callback handler of IRQ target") Signed-off-by: Christophe JAILLET christophe.jaillet@wanadoo.fr
We could test with" if (list_entry_is_head(s, &d->streams, list))" instead, but I find it much less readable.
sound/firewire/amdtp-stream.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index aad9778d1c4d..9be2260e4ca2 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -1943,6 +1943,7 @@ int amdtp_domain_start(struct amdtp_domain *d, unsigned int tx_init_skip_cycles, unsigned int events_per_period = d->events_per_period; unsigned int queue_size; struct amdtp_stream *s;
bool found = false; int err;
if (replay_seq) {
@@ -1955,10 +1956,12 @@ int amdtp_domain_start(struct amdtp_domain *d, unsigned int tx_init_skip_cycles,
// Select an IT context as IRQ target. list_for_each_entry(s, &d->streams, list) {
if (s->direction == AMDTP_OUT_STREAM)
if (s->direction == AMDTP_OUT_STREAM) {found = true; break;}
- if (!s)
- if (!found) return -ENXIO; d->irq_target = s;
-- 2.30.2
Indeed. Nice to catch it. The bug affects Linux kernel v5.5 or later.
Acked-by: Takashi Sakamoto o-takashi@sakamocchi.jp
In kernel v5.10 or later, we can use 'list_entry_is_head()' macro added by a commit e130816164e2 ("include/linux/list.h: add a macro to test if entry is pointing to the head"). However the development of ALSA firewire stack is out-of-tree repository for my convenience to backport it to kernel v4.17 or later (I need testers...), so I prefer your change.
Thanks
Takashi Sakamoto
On Fri, Jun 25, 2021 at 06:05:50AM +0900, Takashi Sakamoto wrote:
In kernel v5.10 or later, we can use 'list_entry_is_head()' macro added by a commit e130816164e2 ("include/linux/list.h: add a macro to test if entry is pointing to the head").
Someone needs to backport that all the way back...
regards, dan carpenter
On Thu, 24 Jun 2021 20:49:36 +0200, Christophe JAILLET wrote:
The intent here is to return an error code if we don't find what we are looking for in the 'list_for_each_entry()' loop.
's' is not NULL if the list is empty or if we scan the complete list. Introduce a new 'found' variable to handle such cases.
Fixes: 60dd49298ec5 ("ALSA: firewire-lib: handle several AMDTP streams in callback handler of IRQ target") Signed-off-by: Christophe JAILLET christophe.jaillet@wanadoo.fr
Applied now. Thanks.
Takashi
We could test with" if (list_entry_is_head(s, &d->streams, list))" instead, but I find it much less readable.
sound/firewire/amdtp-stream.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/sound/firewire/amdtp-stream.c b/sound/firewire/amdtp-stream.c index aad9778d1c4d..9be2260e4ca2 100644 --- a/sound/firewire/amdtp-stream.c +++ b/sound/firewire/amdtp-stream.c @@ -1943,6 +1943,7 @@ int amdtp_domain_start(struct amdtp_domain *d, unsigned int tx_init_skip_cycles, unsigned int events_per_period = d->events_per_period; unsigned int queue_size; struct amdtp_stream *s;
bool found = false; int err;
if (replay_seq) {
@@ -1955,10 +1956,12 @@ int amdtp_domain_start(struct amdtp_domain *d, unsigned int tx_init_skip_cycles,
// Select an IT context as IRQ target. list_for_each_entry(s, &d->streams, list) {
if (s->direction == AMDTP_OUT_STREAM)
if (s->direction == AMDTP_OUT_STREAM) {found = true; break;}
- if (!s)
- if (!found) return -ENXIO; d->irq_target = s;
-- 2.30.2
participants (4)
-
Christophe JAILLET -
Dan Carpenter -
Takashi Iwai -
Takashi Sakamoto