Messages in this thread Patch in this message | | | From | Jakob Koschel <> | Subject | [PATCH 2/3] ARM: pxa: ssp: remove check of list iterator against head past the loop body | Date | Thu, 31 Mar 2022 23:47:18 +0200 |
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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 limit 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> --- arch/arm/plat-pxa/ssp.c | 28 ++++++++++++---------------- 1 file changed, 12 insertions(+), 16 deletions(-)
diff --git a/arch/arm/plat-pxa/ssp.c b/arch/arm/plat-pxa/ssp.c index 563440315acd..6d638f02eac5 100644 --- a/arch/arm/plat-pxa/ssp.c +++ b/arch/arm/plat-pxa/ssp.c @@ -38,22 +38,20 @@ static LIST_HEAD(ssp_list); struct ssp_device *pxa_ssp_request(int port, const char *label) { struct ssp_device *ssp = NULL; + struct ssp_device *iter; mutex_lock(&ssp_lock); - list_for_each_entry(ssp, &ssp_list, node) { - if (ssp->port_id == port && ssp->use_count == 0) { - ssp->use_count++; - ssp->label = label; + list_for_each_entry(iter, &ssp_list, node) { + if (iter->port_id == port && iter->use_count == 0) { + iter->use_count++; + iter->label = label; + ssp = iter; break; } } mutex_unlock(&ssp_lock); - - if (&ssp->node == &ssp_list) - return NULL; - return ssp; } EXPORT_SYMBOL(pxa_ssp_request); @@ -62,22 +60,20 @@ struct ssp_device *pxa_ssp_request_of(const struct device_node *of_node, const char *label) { struct ssp_device *ssp = NULL; + struct ssp_device *iter; mutex_lock(&ssp_lock); - list_for_each_entry(ssp, &ssp_list, node) { - if (ssp->of_node == of_node && ssp->use_count == 0) { - ssp->use_count++; - ssp->label = label; + list_for_each_entry(iter, &ssp_list, node) { + if (iter->of_node == of_node && iter->use_count == 0) { + iter->use_count++; + iter->label = label; + ssp = iter; break; } } mutex_unlock(&ssp_lock); - - if (&ssp->node == &ssp_list) - return NULL; - return ssp; } EXPORT_SYMBOL(pxa_ssp_request_of); -- 2.25.1
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