| Message ID | 1534211696-4221-1-git-send-email-zhongjiang@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm/mach-at91/pm: Do not double put the device node | expand |
On 14/08/2018 09:54:56+0800, zhong jiang wrote: > Device node iterators put the previous value of the index variable, > so an explicit put causes a double put. > While for_each_matching_node_and_match will get and put the node properly, there is also a call to of_find_device_by_node that will get a reference to the node. > I detect the issue with the help of Coccinelle. > > Signed-off-by: zhong jiang <zhongjiang@huawei.com> > --- > arch/arm/mach-at91/pm.c | 5 +---- > 1 file changed, 1 insertion(+), 4 deletions(-) > > diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c > index 32fae4d..a5ec35f 100644 > --- a/arch/arm/mach-at91/pm.c > +++ b/arch/arm/mach-at91/pm.c > @@ -143,15 +143,12 @@ static int at91_pm_config_ws(unsigned int pm_mode, bool set) > > /* Check if enabled on SHDWC. */ > if (wsi->shdwc_mr_bit && !(val & wsi->shdwc_mr_bit)) > - goto put_node; > + continue; > > mode |= wsi->pmc_fsmr_bit; > if (wsi->set_polarity) > polarity |= wsi->pmc_fsmr_bit; > } > - > -put_node: > - of_node_put(np); > } > > if (mode) { > -- > 1.7.12.4 >
Hi Alexandre, On 14.08.2018 15:59, Alexandre Belloni wrote: > On 14/08/2018 09:54:56+0800, zhong jiang wrote: >> Device node iterators put the previous value of the index variable, >> so an explicit put causes a double put. >> > > While for_each_matching_node_and_match will get and put the node > properly, there is also a call to of_find_device_by_node that will get a > reference to the node. > Looking through of_find_device_by_node() it seems that a put_device() on the struct device member of the returned struct platform_device has to be called instead of of_node_put(). of_find_device_by_node() calls bus_find_device(): dev = bus_find_device(&platform_bus_type, NULL, np, of_dev_node_match); the match function, of_dev_node_match(), is just as follows: static int of_dev_node_match(struct device *dev, void *data) { return dev->of_node == data; } but bus_find_device() takes a reference to the struct device returned in case it founds a match, via get_device(): struct device *bus_find_device(struct bus_type *bus, struct device *start, void *data, int (*match)(struct device *dev, void*data)) { struct klist_iter i; struct device *dev; if (!bus || !bus->p) return NULL; klist_iter_init_node(&bus->p->klist_devices, &i, (start ? &start->p->knode_bus : NULL)); while ((dev = next_device(&i))) if (match(dev, data) && get_device(dev)) break; klist_iter_exit(&i); return dev; } So, I think a put_device(&pdev->dev) has to be called in at91_pm_config_ws() instead of of_node_put(np). My bad! Thank you, Claudiu Beznea >> I detect the issue with the help of Coccinelle. >> >> Signed-off-by: zhong jiang <zhongjiang@huawei.com> >> --- >> arch/arm/mach-at91/pm.c | 5 +---- >> 1 file changed, 1 insertion(+), 4 deletions(-) >> >> diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c >> index 32fae4d..a5ec35f 100644 >> --- a/arch/arm/mach-at91/pm.c >> +++ b/arch/arm/mach-at91/pm.c >> @@ -143,15 +143,12 @@ static int at91_pm_config_ws(unsigned int pm_mode, bool set) >> >> /* Check if enabled on SHDWC. */ >> if (wsi->shdwc_mr_bit && !(val & wsi->shdwc_mr_bit)) >> - goto put_node; >> + continue; >> >> mode |= wsi->pmc_fsmr_bit; >> if (wsi->set_polarity) >> polarity |= wsi->pmc_fsmr_bit; >> } >> - >> -put_node: >> - of_node_put(np); >> } >> >> if (mode) { >> -- >> 1.7.12.4 >> >
On 2018/8/16 17:32, Claudiu Beznea wrote: > Hi Alexandre, > > On 14.08.2018 15:59, Alexandre Belloni wrote: >> On 14/08/2018 09:54:56+0800, zhong jiang wrote: >>> Device node iterators put the previous value of the index variable, >>> so an explicit put causes a double put. >>> >> While for_each_matching_node_and_match will get and put the node >> properly, there is also a call to of_find_device_by_node that will get a >> reference to the node. >> > Looking through of_find_device_by_node() it seems that a put_device() on the > struct device member of the returned struct platform_device has to be called > instead of of_node_put(). > > of_find_device_by_node() calls bus_find_device(): > > dev = bus_find_device(&platform_bus_type, NULL, np, of_dev_node_match); > > the match function, of_dev_node_match(), is just as follows: > > static int of_dev_node_match(struct device *dev, void *data) > { > return dev->of_node == data; > } > > but bus_find_device() takes a reference to the struct device returned in case it > founds a match, via get_device(): > > struct device *bus_find_device(struct bus_type *bus, > struct device *start, void *data, > int (*match)(struct device *dev, > void*data)) > { > struct klist_iter i; > struct device *dev; > > if (!bus || !bus->p) > return NULL; > > klist_iter_init_node(&bus->p->klist_devices, &i, > (start ? &start->p->knode_bus : NULL)); > while ((dev = next_device(&i))) > if (match(dev, data) && get_device(dev)) > break; > klist_iter_exit(&i); > return dev; > } > > So, I think a put_device(&pdev->dev) has to be called in at91_pm_config_ws() > instead of of_node_put(np). My bad! Yes, you're right. Thanks, Claudiu. I will repost in v2. Sincerely, zhong jiang > Thank you, > Claudiu Beznea > >>> I detect the issue with the help of Coccinelle. >>> >>> Signed-off-by: zhong jiang <zhongjiang@huawei.com> >>> --- >>> arch/arm/mach-at91/pm.c | 5 +---- >>> 1 file changed, 1 insertion(+), 4 deletions(-) >>> >>> diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c >>> index 32fae4d..a5ec35f 100644 >>> --- a/arch/arm/mach-at91/pm.c >>> +++ b/arch/arm/mach-at91/pm.c >>> @@ -143,15 +143,12 @@ static int at91_pm_config_ws(unsigned int pm_mode, bool set) >>> >>> /* Check if enabled on SHDWC. */ >>> if (wsi->shdwc_mr_bit && !(val & wsi->shdwc_mr_bit)) >>> - goto put_node; >>> + continue; >>> >>> mode |= wsi->pmc_fsmr_bit; >>> if (wsi->set_polarity) >>> polarity |= wsi->pmc_fsmr_bit; >>> } >>> - >>> -put_node: >>> - of_node_put(np); >>> } >>> >>> if (mode) { >>> -- >>> 1.7.12.4 >>> > . >
diff --git a/arch/arm/mach-at91/pm.c b/arch/arm/mach-at91/pm.c index 32fae4d..a5ec35f 100644 --- a/arch/arm/mach-at91/pm.c +++ b/arch/arm/mach-at91/pm.c @@ -143,15 +143,12 @@ static int at91_pm_config_ws(unsigned int pm_mode, bool set) /* Check if enabled on SHDWC. */ if (wsi->shdwc_mr_bit && !(val & wsi->shdwc_mr_bit)) - goto put_node; + continue; mode |= wsi->pmc_fsmr_bit; if (wsi->set_polarity) polarity |= wsi->pmc_fsmr_bit; } - -put_node: - of_node_put(np); } if (mode) {
Device node iterators put the previous value of the index variable, so an explicit put causes a double put. I detect the issue with the help of Coccinelle. Signed-off-by: zhong jiang <zhongjiang@huawei.com> --- arch/arm/mach-at91/pm.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)