| Message ID | 20190831124932.18759-1-yuehaibing@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | [-next] PCI: Use GFP_ATOMIC in resource_alignment_store() | expand |
On Sat, Aug 31, 2019 at 12:49:32PM +0000, YueHaibing wrote: > When allocating memory, the GFP_KERNEL cannot be used during the > spin_lock period. It may cause scheduling when holding spin_lock. > > Fixes: f13755318675 ("PCI: Move pci_[get|set]_resource_alignment_param() into their callers") > Signed-off-by: YueHaibing <yuehaibing@huawei.com> > --- > drivers/pci/pci.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 484e35349565..0b5fc6736f3f 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -6148,7 +6148,7 @@ static ssize_t resource_alignment_store(struct bus_type *bus, > spin_lock(&resource_alignment_lock); > > kfree(resource_alignment_param); > - resource_alignment_param = kstrndup(buf, count, GFP_KERNEL); > + resource_alignment_param = kstrndup(buf, count, GFP_ATOMIC); > > spin_unlock(&resource_alignment_lock); Why not move the allocation outside the lock? Something like this seems much more sensible: diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 484e35349565..fe205829f676 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -6145,14 +6145,16 @@ static ssize_t resource_alignment_show(struct bus_type *bus, char *buf) static ssize_t resource_alignment_store(struct bus_type *bus, const char *buf, size_t count) { - spin_lock(&resource_alignment_lock); + char *param = kstrndup(buf, count, GFP_KERNEL); - kfree(resource_alignment_param); - resource_alignment_param = kstrndup(buf, count, GFP_KERNEL); + if (!param) + return -ENOMEM; + spin_lock(&resource_alignment_lock); + kfree(resource_alignment_param); + resource_alignment_param = param; spin_unlock(&resource_alignment_lock); - - return resource_alignment_param ? count : -ENOMEM; + return count; } static BUS_ATTR_RW(resource_alignment);
On 2019-09-02 1:50 a.m., Christoph Hellwig wrote: > On Sat, Aug 31, 2019 at 12:49:32PM +0000, YueHaibing wrote: >> When allocating memory, the GFP_KERNEL cannot be used during the >> spin_lock period. It may cause scheduling when holding spin_lock. >> >> Fixes: f13755318675 ("PCI: Move pci_[get|set]_resource_alignment_param() into their callers") >> Signed-off-by: YueHaibing <yuehaibing@huawei.com> >> --- >> drivers/pci/pci.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c >> index 484e35349565..0b5fc6736f3f 100644 >> --- a/drivers/pci/pci.c >> +++ b/drivers/pci/pci.c >> @@ -6148,7 +6148,7 @@ static ssize_t resource_alignment_store(struct bus_type *bus, >> spin_lock(&resource_alignment_lock); >> >> kfree(resource_alignment_param); >> - resource_alignment_param = kstrndup(buf, count, GFP_KERNEL); >> + resource_alignment_param = kstrndup(buf, count, GFP_ATOMIC); >> >> spin_unlock(&resource_alignment_lock); > > Why not move the allocation outside the lock? Something like this > seems much more sensible: Yes, that seems like a good way to do it. Bjorn, can you squash Christoph's patch or do you want me to resend a new one? Thanks, Logan > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 484e35349565..fe205829f676 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -6145,14 +6145,16 @@ static ssize_t resource_alignment_show(struct bus_type *bus, char *buf) > static ssize_t resource_alignment_store(struct bus_type *bus, > const char *buf, size_t count) > { > - spin_lock(&resource_alignment_lock); > + char *param = kstrndup(buf, count, GFP_KERNEL); > > - kfree(resource_alignment_param); > - resource_alignment_param = kstrndup(buf, count, GFP_KERNEL); > + if (!param) > + return -ENOMEM; > > + spin_lock(&resource_alignment_lock); > + kfree(resource_alignment_param); > + resource_alignment_param = param; > spin_unlock(&resource_alignment_lock); > - > - return resource_alignment_param ? count : -ENOMEM; > + return count; > } > > static BUS_ATTR_RW(resource_alignment); >
On Tue, Sep 03, 2019 at 09:51:05AM -0600, Logan Gunthorpe wrote: > > > On 2019-09-02 1:50 a.m., Christoph Hellwig wrote: > > On Sat, Aug 31, 2019 at 12:49:32PM +0000, YueHaibing wrote: > >> When allocating memory, the GFP_KERNEL cannot be used during the > >> spin_lock period. It may cause scheduling when holding spin_lock. > >> > >> Fixes: f13755318675 ("PCI: Move pci_[get|set]_resource_alignment_param() into their callers") > >> Signed-off-by: YueHaibing <yuehaibing@huawei.com> > >> --- > >> drivers/pci/pci.c | 2 +- > >> 1 file changed, 1 insertion(+), 1 deletion(-) > >> > >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > >> index 484e35349565..0b5fc6736f3f 100644 > >> --- a/drivers/pci/pci.c > >> +++ b/drivers/pci/pci.c > >> @@ -6148,7 +6148,7 @@ static ssize_t resource_alignment_store(struct bus_type *bus, > >> spin_lock(&resource_alignment_lock); > >> > >> kfree(resource_alignment_param); > >> - resource_alignment_param = kstrndup(buf, count, GFP_KERNEL); > >> + resource_alignment_param = kstrndup(buf, count, GFP_ATOMIC); > >> > >> spin_unlock(&resource_alignment_lock); > > > > Why not move the allocation outside the lock? Something like this > > seems much more sensible: > > Yes, that seems like a good way to do it. Bjorn, can you squash > Christoph's patch or do you want me to resend a new one? I folded Christoph's fix into it, thanks! > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > > index 484e35349565..fe205829f676 100644 > > --- a/drivers/pci/pci.c > > +++ b/drivers/pci/pci.c > > @@ -6145,14 +6145,16 @@ static ssize_t resource_alignment_show(struct bus_type *bus, char *buf) > > static ssize_t resource_alignment_store(struct bus_type *bus, > > const char *buf, size_t count) > > { > > - spin_lock(&resource_alignment_lock); > > + char *param = kstrndup(buf, count, GFP_KERNEL); > > > > - kfree(resource_alignment_param); > > - resource_alignment_param = kstrndup(buf, count, GFP_KERNEL); > > + if (!param) > > + return -ENOMEM; > > > > + spin_lock(&resource_alignment_lock); > > + kfree(resource_alignment_param); > > + resource_alignment_param = param; > > spin_unlock(&resource_alignment_lock); > > - > > - return resource_alignment_param ? count : -ENOMEM; > > + return count; > > } > > > > static BUS_ATTR_RW(resource_alignment); > >
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 484e35349565..0b5fc6736f3f 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -6148,7 +6148,7 @@ static ssize_t resource_alignment_store(struct bus_type *bus, spin_lock(&resource_alignment_lock); kfree(resource_alignment_param); - resource_alignment_param = kstrndup(buf, count, GFP_KERNEL); + resource_alignment_param = kstrndup(buf, count, GFP_ATOMIC); spin_unlock(&resource_alignment_lock);
When allocating memory, the GFP_KERNEL cannot be used during the spin_lock period. It may cause scheduling when holding spin_lock. Fixes: f13755318675 ("PCI: Move pci_[get|set]_resource_alignment_param() into their callers") Signed-off-by: YueHaibing <yuehaibing@huawei.com> --- drivers/pci/pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)