Add a helper for enabling link states that can be used in contexts where a pci_bus_sem read lock is already held (e.g. from pci_walk_bus()).
This helper will be used to fix a couple of potential deadlocks where the current helper is called with the lock already held, hence the CC stable tag.
Fixes: f492edb40b54 ("PCI: vmd: Add quirk to configure PCIe ASPM and LTR") Cc: stable@vger.kernel.org # 6.3 Cc: Michael Bottini michael.a.bottini@linux.intel.com Cc: David E. Box david.e.box@linux.intel.com Signed-off-by: Johan Hovold johan+linaro@kernel.org --- drivers/pci/pcie/aspm.c | 53 +++++++++++++++++++++++++++++++---------- include/linux/pci.h | 3 +++ 2 files changed, 43 insertions(+), 13 deletions(-)
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 50b04ae5c394..8cf8cc2d6bba 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1109,17 +1109,7 @@ int pci_disable_link_state(struct pci_dev *pdev, int state) } EXPORT_SYMBOL(pci_disable_link_state);
-/** - * pci_enable_link_state - Clear and set the default device link state so that - * the link may be allowed to enter the specified states. Note that if the - * BIOS didn't grant ASPM control to the OS, this does nothing because we can't - * touch the LNKCTL register. Also note that this does not enable states - * disabled by pci_disable_link_state(). Return 0 or a negative errno. - * - * @pdev: PCI device - * @state: Mask of ASPM link states to enable - */ -int pci_enable_link_state(struct pci_dev *pdev, int state) +static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) { struct pcie_link_state *link = pcie_aspm_get_link(pdev);
@@ -1136,7 +1126,8 @@ int pci_enable_link_state(struct pci_dev *pdev, int state) return -EPERM; }
- down_read(&pci_bus_sem); + if (!locked) + down_read(&pci_bus_sem); mutex_lock(&aspm_lock); link->aspm_default = 0; if (state & PCIE_LINK_STATE_L0S) @@ -1157,12 +1148,48 @@ int pci_enable_link_state(struct pci_dev *pdev, int state) link->clkpm_default = (state & PCIE_LINK_STATE_CLKPM) ? 1 : 0; pcie_set_clkpm(link, policy_to_clkpm_state(link)); mutex_unlock(&aspm_lock); - up_read(&pci_bus_sem); + if (!locked) + up_read(&pci_bus_sem);
return 0; } + +/** + * pci_enable_link_state - Clear and set the default device link state so that + * the link may be allowed to enter the specified states. Note that if the + * BIOS didn't grant ASPM control to the OS, this does nothing because we can't + * touch the LNKCTL register. Also note that this does not enable states + * disabled by pci_disable_link_state(). Return 0 or a negative errno. + * + * @pdev: PCI device + * @state: Mask of ASPM link states to enable + */ +int pci_enable_link_state(struct pci_dev *pdev, int state) +{ + return __pci_enable_link_state(pdev, state, false); +} EXPORT_SYMBOL(pci_enable_link_state);
+/** + * pci_enable_link_state - Clear and set the default device link state so that + * the link may be allowed to enter the specified states. Note that if the + * BIOS didn't grant ASPM control to the OS, this does nothing because we can't + * touch the LNKCTL register. Also note that this does not enable states + * disabled by pci_disable_link_state(). Return 0 or a negative errno. + * + * @pdev: PCI device + * @state: Mask of ASPM link states to enable + * + * Context: Caller holds pci_bus_sem read lock. + */ +int pci_enable_link_state_locked(struct pci_dev *pdev, int state) +{ + lockdep_assert_held_read(&pci_bus_sem); + + return __pci_enable_link_state(pdev, state, true); +} +EXPORT_SYMBOL(pci_enable_link_state_locked); + static int pcie_aspm_set_policy(const char *val, const struct kernel_param *kp) { diff --git a/include/linux/pci.h b/include/linux/pci.h index 60ca768bc867..dea043bc1e38 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1829,6 +1829,7 @@ extern bool pcie_ports_native; int pci_disable_link_state(struct pci_dev *pdev, int state); int pci_disable_link_state_locked(struct pci_dev *pdev, int state); int pci_enable_link_state(struct pci_dev *pdev, int state); +int pci_enable_link_state_locked(struct pci_dev *pdev, int state); void pcie_no_aspm(void); bool pcie_aspm_support_enabled(void); bool pcie_aspm_enabled(struct pci_dev *pdev); @@ -1839,6 +1840,8 @@ static inline int pci_disable_link_state_locked(struct pci_dev *pdev, int state) { return 0; } static inline int pci_enable_link_state(struct pci_dev *pdev, int state) { return 0; } +static inline int pci_enable_link_state_locked(struct pci_dev *pdev, int state) +{ return 0; } static inline void pcie_no_aspm(void) { } static inline bool pcie_aspm_support_enabled(void) { return false; } static inline bool pcie_aspm_enabled(struct pci_dev *pdev) { return false; }
Hi Johan,
kernel test robot noticed the following build warnings:
[auto build test WARNING on pci/next] [also build test WARNING on pci/for-linus linus/master v6.7-rc1 next-20231115] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Johan-Hovold/PCI-ASPM-Add-loc... base: https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git next patch link: https://lore.kernel.org/r/20231114135553.32301-2-johan%2Blinaro%40kernel.org patch subject: [PATCH 1/6] PCI/ASPM: Add locked helper for enabling link state config: x86_64-randconfig-002-20231115 (https://download.01.org/0day-ci/archive/20231115/202311152225.ZdVv0ufT-lkp@i...) compiler: gcc-12 (Debian 12.2.0-14) 12.2.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20231115/202311152225.ZdVv0ufT-lkp@i...)
If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot lkp@intel.com | Closes: https://lore.kernel.org/oe-kbuild-all/202311152225.ZdVv0ufT-lkp@intel.com/
All warnings (new ones prefixed by >>):
drivers/pci/pcie/aspm.c:1186: warning: expecting prototype for pci_enable_link_state(). Prototype was for pci_enable_link_state_locked() instead
vim +1186 drivers/pci/pcie/aspm.c
1172 1173 /** 1174 * pci_enable_link_state - Clear and set the default device link state so that 1175 * the link may be allowed to enter the specified states. Note that if the 1176 * BIOS didn't grant ASPM control to the OS, this does nothing because we can't 1177 * touch the LNKCTL register. Also note that this does not enable states 1178 * disabled by pci_disable_link_state(). Return 0 or a negative errno. 1179 * 1180 * @pdev: PCI device 1181 * @state: Mask of ASPM link states to enable 1182 * 1183 * Context: Caller holds pci_bus_sem read lock. 1184 */ 1185 int pci_enable_link_state_locked(struct pci_dev *pdev, int state)
1186 {
1187 lockdep_assert_held_read(&pci_bus_sem); 1188 1189 return __pci_enable_link_state(pdev, state, true); 1190 } 1191 EXPORT_SYMBOL(pci_enable_link_state_locked); 1192
On Wed, Nov 15, 2023 at 10:26:40PM +0800, kernel test robot wrote:
drivers/pci/pcie/aspm.c:1186: warning: expecting prototype for pci_enable_link_state(). Prototype was for pci_enable_link_state_locked() instead
vim +1186 drivers/pci/pcie/aspm.c
1172 1173 /** 1174 * pci_enable_link_state - Clear and set the default device link state so that
I apparently forgot to update the name here to
pci_enable_link_state_locked
[ ... ]
1184 */ 1185 int pci_enable_link_state_locked(struct pci_dev *pdev, int state)
Perhaps this can be fixed up when applying, or otherwise I'll respin.
Johan
On Wed, Nov 15, 2023 at 05:06:23PM +0100, Johan Hovold wrote:
On Wed, Nov 15, 2023 at 10:26:40PM +0800, kernel test robot wrote:
drivers/pci/pcie/aspm.c:1186: warning: expecting prototype for pci_enable_link_state(). Prototype was for pci_enable_link_state_locked() instead
vim +1186 drivers/pci/pcie/aspm.c
1172 1173 /** 1174 * pci_enable_link_state - Clear and set the default device link state so that
I apparently forgot to update the name here to
pci_enable_link_state_locked
While fixing the name, please add locking information in description as well.
- Mani
[ ... ]
1184 */ 1185 int pci_enable_link_state_locked(struct pci_dev *pdev, int state)
Perhaps this can be fixed up when applying, or otherwise I'll respin.
Johan
On Fri, Nov 17, 2023 at 03:57:24PM +0530, Manivannan Sadhasivam wrote:
On Wed, Nov 15, 2023 at 05:06:23PM +0100, Johan Hovold wrote:
On Wed, Nov 15, 2023 at 10:26:40PM +0800, kernel test robot wrote:
drivers/pci/pcie/aspm.c:1186: warning: expecting prototype for pci_enable_link_state(). Prototype was for pci_enable_link_state_locked() instead
vim +1186 drivers/pci/pcie/aspm.c
1172 1173 /** 1174 * pci_enable_link_state - Clear and set the default device link state so that
I apparently forgot to update the name here to
pci_enable_link_state_locked
While fixing the name, please add locking information in description as well.
It's already there:
Context: Caller holds pci_bus_sem read lock.
Johan
On Fri, Nov 17, 2023 at 11:30:39AM +0100, Johan Hovold wrote:
On Fri, Nov 17, 2023 at 03:57:24PM +0530, Manivannan Sadhasivam wrote:
On Wed, Nov 15, 2023 at 05:06:23PM +0100, Johan Hovold wrote:
On Wed, Nov 15, 2023 at 10:26:40PM +0800, kernel test robot wrote:
drivers/pci/pcie/aspm.c:1186: warning: expecting prototype for pci_enable_link_state(). Prototype was for pci_enable_link_state_locked() instead
vim +1186 drivers/pci/pcie/aspm.c
1172 1173 /** 1174 * pci_enable_link_state - Clear and set the default device link state so that
I apparently forgot to update the name here to
pci_enable_link_state_locked
While fixing the name, please add locking information in description as well.
It's already there:
Context: Caller holds pci_bus_sem read lock.
Ah, I was looking for it in the description. Fine then!
- Mani
Johan
On Tue, Nov 14, 2023 at 02:55:48PM +0100, Johan Hovold wrote:
Add a helper for enabling link states that can be used in contexts where a pci_bus_sem read lock is already held (e.g. from pci_walk_bus()).
This helper will be used to fix a couple of potential deadlocks where the current helper is called with the lock already held, hence the CC stable tag.
Fixes: f492edb40b54 ("PCI: vmd: Add quirk to configure PCIe ASPM and LTR") Cc: stable@vger.kernel.org # 6.3 Cc: Michael Bottini michael.a.bottini@linux.intel.com Cc: David E. Box david.e.box@linux.intel.com Signed-off-by: Johan Hovold johan+linaro@kernel.org
With the Kdoc comment fixed,
Reviewed-by: Manivannan Sadhasivam manivannan.sadhasivam@linaro.org
- Mani
drivers/pci/pcie/aspm.c | 53 +++++++++++++++++++++++++++++++---------- include/linux/pci.h | 3 +++ 2 files changed, 43 insertions(+), 13 deletions(-)
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 50b04ae5c394..8cf8cc2d6bba 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1109,17 +1109,7 @@ int pci_disable_link_state(struct pci_dev *pdev, int state) } EXPORT_SYMBOL(pci_disable_link_state); -/**
- pci_enable_link_state - Clear and set the default device link state so that
- the link may be allowed to enter the specified states. Note that if the
- BIOS didn't grant ASPM control to the OS, this does nothing because we can't
- touch the LNKCTL register. Also note that this does not enable states
- disabled by pci_disable_link_state(). Return 0 or a negative errno.
- @pdev: PCI device
- @state: Mask of ASPM link states to enable
- */
-int pci_enable_link_state(struct pci_dev *pdev, int state) +static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) { struct pcie_link_state *link = pcie_aspm_get_link(pdev); @@ -1136,7 +1126,8 @@ int pci_enable_link_state(struct pci_dev *pdev, int state) return -EPERM; }
- down_read(&pci_bus_sem);
- if (!locked)
down_read(&pci_bus_sem);@@ -1157,12 +1148,48 @@ int pci_enable_link_state(struct pci_dev *pdev, int state) link->clkpm_default = (state & PCIE_LINK_STATE_CLKPM) ? 1 : 0; pcie_set_clkpm(link, policy_to_clkpm_state(link)); mutex_unlock(&aspm_lock);
- up_read(&pci_bus_sem);
- if (!locked)
up_read(&pci_bus_sem);return 0; }
+/**
- pci_enable_link_state - Clear and set the default device link state so that
- the link may be allowed to enter the specified states. Note that if the
- BIOS didn't grant ASPM control to the OS, this does nothing because we can't
- touch the LNKCTL register. Also note that this does not enable states
- disabled by pci_disable_link_state(). Return 0 or a negative errno.
- @pdev: PCI device
- @state: Mask of ASPM link states to enable
- */
+int pci_enable_link_state(struct pci_dev *pdev, int state) +{
- return __pci_enable_link_state(pdev, state, false);
+} EXPORT_SYMBOL(pci_enable_link_state); +/**
- pci_enable_link_state - Clear and set the default device link state so that
- the link may be allowed to enter the specified states. Note that if the
- BIOS didn't grant ASPM control to the OS, this does nothing because we can't
- touch the LNKCTL register. Also note that this does not enable states
- disabled by pci_disable_link_state(). Return 0 or a negative errno.
- @pdev: PCI device
- @state: Mask of ASPM link states to enable
- Context: Caller holds pci_bus_sem read lock.
- */
+int pci_enable_link_state_locked(struct pci_dev *pdev, int state) +{
- lockdep_assert_held_read(&pci_bus_sem);
- return __pci_enable_link_state(pdev, state, true);
+} +EXPORT_SYMBOL(pci_enable_link_state_locked);
static int pcie_aspm_set_policy(const char *val, const struct kernel_param *kp) { diff --git a/include/linux/pci.h b/include/linux/pci.h index 60ca768bc867..dea043bc1e38 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1829,6 +1829,7 @@ extern bool pcie_ports_native; int pci_disable_link_state(struct pci_dev *pdev, int state); int pci_disable_link_state_locked(struct pci_dev *pdev, int state); int pci_enable_link_state(struct pci_dev *pdev, int state); +int pci_enable_link_state_locked(struct pci_dev *pdev, int state); void pcie_no_aspm(void); bool pcie_aspm_support_enabled(void); bool pcie_aspm_enabled(struct pci_dev *pdev); @@ -1839,6 +1840,8 @@ static inline int pci_disable_link_state_locked(struct pci_dev *pdev, int state) { return 0; } static inline int pci_enable_link_state(struct pci_dev *pdev, int state) { return 0; } +static inline int pci_enable_link_state_locked(struct pci_dev *pdev, int state) +{ return 0; } static inline void pcie_no_aspm(void) { } static inline bool pcie_aspm_support_enabled(void) { return false; } static inline bool pcie_aspm_enabled(struct pci_dev *pdev) { return false; } -- 2.41.0
On Tue, 2023-11-14 at 14:55 +0100, Johan Hovold wrote:
Add a helper for enabling link states that can be used in contexts where a pci_bus_sem read lock is already held (e.g. from pci_walk_bus()).
This helper will be used to fix a couple of potential deadlocks where the current helper is called with the lock already held, hence the CC stable tag.
Thanks for sending a patch to address this. It had fallen off my radar.
Fixes: f492edb40b54 ("PCI: vmd: Add quirk to configure PCIe ASPM and LTR") Cc: stable@vger.kernel.org # 6.3 Cc: Michael Bottini michael.a.bottini@linux.intel.com Cc: David E. Box david.e.box@linux.intel.com Signed-off-by: Johan Hovold johan+linaro@kernel.org
drivers/pci/pcie/aspm.c | 53 +++++++++++++++++++++++++++++++---------- include/linux/pci.h | 3 +++ 2 files changed, 43 insertions(+), 13 deletions(-)
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c index 50b04ae5c394..8cf8cc2d6bba 100644 --- a/drivers/pci/pcie/aspm.c +++ b/drivers/pci/pcie/aspm.c @@ -1109,17 +1109,7 @@ int pci_disable_link_state(struct pci_dev *pdev, int state) } EXPORT_SYMBOL(pci_disable_link_state); -/**
- pci_enable_link_state - Clear and set the default device link state so
that
- the link may be allowed to enter the specified states. Note that if the
- BIOS didn't grant ASPM control to the OS, this does nothing because we
can't
- touch the LNKCTL register. Also note that this does not enable states
- disabled by pci_disable_link_state(). Return 0 or a negative errno.
- @pdev: PCI device
- @state: Mask of ASPM link states to enable
- */
-int pci_enable_link_state(struct pci_dev *pdev, int state) +static int __pci_enable_link_state(struct pci_dev *pdev, int state, bool locked) { struct pcie_link_state *link = pcie_aspm_get_link(pdev); @@ -1136,7 +1126,8 @@ int pci_enable_link_state(struct pci_dev *pdev, int state) return -EPERM; } - down_read(&pci_bus_sem); + if (!locked) + down_read(&pci_bus_sem);
This solution is similar to the original one I proposed [1]. It just creates a separate locked function rather than using a flag. While the API is consistent with pci_disable_link_state_locked(), its usage is not. The vmd driver calls pci_enable_link_state() from pci_walk_bus() which was problematic for Bjorn [2]. I owed an attempt to implement this as a fixup. However, now qcom_pcie_enabled_aspm() is also using it from pci_walk_bus(). The fixup could make sense for VMD since there it's fixing missing BIOS settings, but I'm not sure about qcom. Bjorn, do you still see issues with the use in pci_bus_walk()?
[1] https://lore.kernel.org/lkml/20230321233849.3408339-1-david.e.box@linux.inte...
[2] https://lore.kernel.org/lkml/20230322205702.GA2493123@bhelgaas/
David
mutex_lock(&aspm_lock); link->aspm_default = 0; if (state & PCIE_LINK_STATE_L0S) @@ -1157,12 +1148,48 @@ int pci_enable_link_state(struct pci_dev *pdev, int state) link->clkpm_default = (state & PCIE_LINK_STATE_CLKPM) ? 1 : 0; pcie_set_clkpm(link, policy_to_clkpm_state(link)); mutex_unlock(&aspm_lock); - up_read(&pci_bus_sem); + if (!locked) + up_read(&pci_bus_sem); return 0; }
+/**
- pci_enable_link_state - Clear and set the default device link state so
that
- the link may be allowed to enter the specified states. Note that if the
- BIOS didn't grant ASPM control to the OS, this does nothing because we
can't
- touch the LNKCTL register. Also note that this does not enable states
- disabled by pci_disable_link_state(). Return 0 or a negative errno.
- @pdev: PCI device
- @state: Mask of ASPM link states to enable
- */
+int pci_enable_link_state(struct pci_dev *pdev, int state) +{ + return __pci_enable_link_state(pdev, state, false); +} EXPORT_SYMBOL(pci_enable_link_state); +/**
- pci_enable_link_state - Clear and set the default device link state so
that
- the link may be allowed to enter the specified states. Note that if the
- BIOS didn't grant ASPM control to the OS, this does nothing because we
can't
- touch the LNKCTL register. Also note that this does not enable states
- disabled by pci_disable_link_state(). Return 0 or a negative errno.
- @pdev: PCI device
- @state: Mask of ASPM link states to enable
- Context: Caller holds pci_bus_sem read lock.
- */
+int pci_enable_link_state_locked(struct pci_dev *pdev, int state) +{ + lockdep_assert_held_read(&pci_bus_sem);
+ return __pci_enable_link_state(pdev, state, true); +} +EXPORT_SYMBOL(pci_enable_link_state_locked);
static int pcie_aspm_set_policy(const char *val, const struct kernel_param *kp) { diff --git a/include/linux/pci.h b/include/linux/pci.h index 60ca768bc867..dea043bc1e38 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1829,6 +1829,7 @@ extern bool pcie_ports_native; int pci_disable_link_state(struct pci_dev *pdev, int state); int pci_disable_link_state_locked(struct pci_dev *pdev, int state); int pci_enable_link_state(struct pci_dev *pdev, int state); +int pci_enable_link_state_locked(struct pci_dev *pdev, int state); void pcie_no_aspm(void); bool pcie_aspm_support_enabled(void); bool pcie_aspm_enabled(struct pci_dev *pdev); @@ -1839,6 +1840,8 @@ static inline int pci_disable_link_state_locked(struct pci_dev *pdev, int state) { return 0; } static inline int pci_enable_link_state(struct pci_dev *pdev, int state) { return 0; } +static inline int pci_enable_link_state_locked(struct pci_dev *pdev, int state) +{ return 0; } static inline void pcie_no_aspm(void) { } static inline bool pcie_aspm_support_enabled(void) { return false; } static inline bool pcie_aspm_enabled(struct pci_dev *pdev) { return false; }
On Fri, Nov 17, 2023 at 04:00:46PM -0800, David E. Box wrote:
On Tue, 2023-11-14 at 14:55 +0100, Johan Hovold wrote:
Add a helper for enabling link states that can be used in contexts where a pci_bus_sem read lock is already held (e.g. from pci_walk_bus()).
This helper will be used to fix a couple of potential deadlocks where the current helper is called with the lock already held, hence the CC stable tag.
This solution is similar to the original one I proposed [1]. It just creates a separate locked function rather than using a flag. While the API is consistent with pci_disable_link_state_locked(), its usage is not. The vmd driver calls pci_enable_link_state() from pci_walk_bus() which was problematic for Bjorn [2]. I owed an attempt to implement this as a fixup. However, now qcom_pcie_enabled_aspm() is also using it from pci_walk_bus(). The fixup could make sense for VMD since there it's fixing missing BIOS settings, but I'm not sure about qcom. Bjorn, do you still see issues with the use in pci_bus_walk()?
We need this for Qualcomm platforms where the boot firmware does not enable ASPM, and the hotplug inconsistency was also discussed with Bjorn here:
https://lore.kernel.org/linux-pci/20231018164731.GA1365588@bhelgaas/
[1] https://lore.kernel.org/lkml/20230321233849.3408339-1-david.e.box@linux.inte...
[2] https://lore.kernel.org/lkml/20230322205702.GA2493123@bhelgaas/
Johan
linux-stable-mirror@lists.linaro.org
-
David E. Box -
Johan Hovold -
Johan Hovold -
kernel test robot -
Manivannan Sadhasivam