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| author |   Lukas Wunner <lukas@wunner.de> | 2019-08-09 12:28:43 +0200 |
|---|---|---|
| committer |   Bjorn Helgaas <bhelgaas@google.com> | 2019-10-04 15:39:36 -0500 |
| commit | 157c1062fcd86ade3c674503705033051fd3d401 (patch) | |
| tree | 78038be473f0c5df2880a57ce078df1f7d4806b5 /drivers/pci/hotplug/pciehp.h | |
| parent | Linux 5.4-rc1 (diff) | |
| download | linux-dev-157c1062fcd86ade3c674503705033051fd3d401.tar.xz linux-dev-157c1062fcd86ade3c674503705033051fd3d401.zip | |
PCI: pciehp: Avoid returning prematurely from sysfs requests
A sysfs request to enable or disable a PCIe hotplug slot should not
return before it has been carried out. That is sought to be achieved by
waiting until the controller's "pending_events" have been cleared.
However the IRQ thread pciehp_ist() clears the "pending_events" before
it acts on them. If pciehp_sysfs_enable_slot() / _disable_slot() happen
to check the "pending_events" after they have been cleared but while
pciehp_ist() is still running, the functions may return prematurely
with an incorrect return value.
Fix by introducing an "ist_running" flag which must be false before a sysfs
request is allowed to return.
Fixes: 32a8cef274fe ("PCI: pciehp: Enable/disable exclusively from IRQ thread")
Link: https://lore.kernel.org/linux-pci/1562226638-54134-1-git-send-email-wangxiongfeng2@huawei.com
Link: https://lore.kernel.org/r/4174210466e27eb7e2243dd1d801d5f75baaffd8.1565345211.git.lukas@wunner.de
Reported-and-tested-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org # v4.19+
Diffstat (limited to 'drivers/pci/hotplug/pciehp.h')
| -rw-r--r-- | drivers/pci/hotplug/pciehp.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h index 654c972b8ea0..882ce82c4699 100644 --- a/drivers/pci/hotplug/pciehp.h +++ b/drivers/pci/hotplug/pciehp.h @@ -72,6 +72,7 @@ extern int pciehp_poll_time; * @reset_lock: prevents access to the Data Link Layer Link Active bit in the * Link Status register and to the Presence Detect State bit in the Slot * Status register during a slot reset which may cause them to flap + * @ist_running: flag to keep user request waiting while IRQ thread is running * @request_result: result of last user request submitted to the IRQ thread * @requester: wait queue to wake up on completion of user request, * used for synchronous slot enable/disable request via sysfs @@ -101,6 +102,7 @@ struct controller { struct hotplug_slot hotplug_slot; /* hotplug core interface */ struct rw_semaphore reset_lock; + unsigned int ist_running; int request_result; wait_queue_head_t requester; }; |