| Message ID | 20220331215003.882143-1-jakobkoschel@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [1/3] ASoC: Intel: catpt: remove check of list iterator against head past the loop body | expand |
On Fri, Apr 1, 2022 at 5:52 AM Jakob Koschel <jakobkoschel@gmail.com> wrote: > > When list_for_each_entry() completes the iteration over the whole list > without breaking the loop, the iterator value will be a bogus pointer > computed based on the head element. > > While it is safe to use the pointer to determine if it was computed > based on the head element, either with list_entry_is_head() or > &pos->member == head, using the iterator variable after the loop should > be avoided. > > In preparation to limiting the scope of a list iterator to the list > traversal loop, use a dedicated pointer to point to the found element [1]. > > Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1] > Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com> LGTM. Thanks. Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> > sound/soc/sprd/sprd-mcdt.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/sound/soc/sprd/sprd-mcdt.c b/sound/soc/sprd/sprd-mcdt.c > index f6a55fa60c1b..6e27789a0df5 100644 > --- a/sound/soc/sprd/sprd-mcdt.c > +++ b/sound/soc/sprd/sprd-mcdt.c > @@ -866,20 +866,19 @@ EXPORT_SYMBOL_GPL(sprd_mcdt_chan_dma_disable); > struct sprd_mcdt_chan *sprd_mcdt_request_chan(u8 channel, > enum sprd_mcdt_channel_type type) > { > - struct sprd_mcdt_chan *temp; > + struct sprd_mcdt_chan *temp = NULL; > + struct sprd_mcdt_chan *iter; > > mutex_lock(&sprd_mcdt_list_mutex); > > - list_for_each_entry(temp, &sprd_mcdt_chan_list, list) { > - if (temp->type == type && temp->id == channel) { > - list_del_init(&temp->list); > + list_for_each_entry(iter, &sprd_mcdt_chan_list, list) { > + if (iter->type == type && iter->id == channel) { > + list_del_init(&iter->list); > + temp = iter; > break; > } > } > > - if (list_entry_is_head(temp, &sprd_mcdt_chan_list, list)) > - temp = NULL; > - > mutex_unlock(&sprd_mcdt_list_mutex); > > return temp; > -- > 2.25.1 >
On 2022-03-31 11:50 PM, Jakob Koschel wrote: > When list_for_each_entry() completes the iteration over the whole list > without breaking the loop, the iterator value will be a bogus pointer > computed based on the head element. > > While it is safe to use the pointer to determine if it was computed > based on the head element, either with list_entry_is_head() or > &pos->member == head, using the iterator variable after the loop should > be avoided. > > In preparation to limiting the scope of a list iterator to the list > traversal loop, use a dedicated pointer to point to the found element [1]. > > Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1] > Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com> Thank you for taking time and updating catpt-driver along the way. Acked-by: Cezary Rojewski <cezary.rojewski@intel.com> > --- > sound/soc/intel/catpt/pcm.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/sound/soc/intel/catpt/pcm.c b/sound/soc/intel/catpt/pcm.c > index a26000cd5ceb..b103b2d4026e 100644 > --- a/sound/soc/intel/catpt/pcm.c > +++ b/sound/soc/intel/catpt/pcm.c > @@ -330,7 +330,8 @@ static int catpt_dai_apply_usettings(struct snd_soc_dai *dai, > struct catpt_stream_runtime *stream) > { > struct snd_soc_component *component = dai->component; > - struct snd_kcontrol *pos; > + struct snd_kcontrol *pos = NULL; > + struct snd_kcontrol *iter; > struct catpt_dev *cdev = dev_get_drvdata(dai->dev); > const char *name; > int ret; > @@ -354,12 +355,14 @@ static int catpt_dai_apply_usettings(struct snd_soc_dai *dai, > return 0; > } > > - list_for_each_entry(pos, &component->card->snd_card->controls, list) { > - if (pos->private_data == component && > - !strncmp(name, pos->id.name, sizeof(pos->id.name))) > + list_for_each_entry(iter, &component->card->snd_card->controls, list) { > + if (iter->private_data == component && > + !strncmp(name, iter->id.name, sizeof(iter->id.name))) { > + pos = iter; > break; > + } > } > - if (list_entry_is_head(pos, &component->card->snd_card->controls, list)) > + if (!pos) > return -ENOENT; > > if (stream->template->type != CATPT_STRM_TYPE_LOOPBACK) > > base-commit: f82da161ea75dc4db21b2499e4b1facd36dab275
diff --git a/sound/soc/intel/catpt/pcm.c b/sound/soc/intel/catpt/pcm.c index a26000cd5ceb..b103b2d4026e 100644 --- a/sound/soc/intel/catpt/pcm.c +++ b/sound/soc/intel/catpt/pcm.c @@ -330,7 +330,8 @@ static int catpt_dai_apply_usettings(struct snd_soc_dai *dai, struct catpt_stream_runtime *stream) { struct snd_soc_component *component = dai->component; - struct snd_kcontrol *pos; + struct snd_kcontrol *pos = NULL; + struct snd_kcontrol *iter; struct catpt_dev *cdev = dev_get_drvdata(dai->dev); const char *name; int ret; @@ -354,12 +355,14 @@ static int catpt_dai_apply_usettings(struct snd_soc_dai *dai, return 0; } - list_for_each_entry(pos, &component->card->snd_card->controls, list) { - if (pos->private_data == component && - !strncmp(name, pos->id.name, sizeof(pos->id.name))) + list_for_each_entry(iter, &component->card->snd_card->controls, list) { + if (iter->private_data == component && + !strncmp(name, iter->id.name, sizeof(iter->id.name))) { + pos = iter; break; + } } - if (list_entry_is_head(pos, &component->card->snd_card->controls, list)) + if (!pos) return -ENOENT; if (stream->template->type != CATPT_STRM_TYPE_LOOPBACK)
When list_for_each_entry() completes the iteration over the whole list without breaking the loop, the iterator value will be a bogus pointer computed based on the head element. While it is safe to use the pointer to determine if it was computed based on the head element, either with list_entry_is_head() or &pos->member == head, using the iterator variable after the loop should be avoided. In preparation to limiting the scope of a list iterator to the list traversal loop, use a dedicated pointer to point to the found element [1]. Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1] Signed-off-by: Jakob Koschel <jakobkoschel@gmail.com> --- sound/soc/intel/catpt/pcm.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) base-commit: f82da161ea75dc4db21b2499e4b1facd36dab275