| Message ID | 20231128081512.19387-1-johan+linaro@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | PCI: Fix deadlocks when enabling ASPM | expand |
Hi PCI maintainers, On Tue, Nov 28, 2023 at 09:15:06AM +0100, Johan Hovold wrote: > The pci_enable_link_state() helper is currently only called from > pci_walk_bus(), something which can lead to a deadlock as both helpers > take a pci_bus_sem read lock. > > Add a new locked helper which can be called with the read lock held and > fix up the two current users (the second is new in 6.7-rc1). > > Note that there are no users left of the original unlocked variant after > this series, but I decided to leave it in place for now (e.g. to mirror > the corresponding helpers to disable link states). > > Included are also a couple of related cleanups. > Johan Hovold (6): > PCI/ASPM: Add locked helper for enabling link state > PCI: vmd: Fix deadlock when enabling ASPM > PCI: qcom: Fix deadlock when enabling ASPM > PCI: qcom: Clean up ASPM comment > PCI/ASPM: Clean up disable link state parameter > PCI/ASPM: Add lockdep assert to link state helper Could we get this merged for 6.7-rc5? Even if the risk of a deadlock is not that great, this bug prevents using lockdep on Qualcomm platforms so that more locking issues can potentially make their way into the kernel. And for Qualcomm platforms, this is a regression in 6.7-rc1. Johan #regzbot introduced: 9f4f3dfad8cf
On Tue, Nov 28, 2023 at 09:15:06AM +0100, Johan Hovold wrote: > The pci_enable_link_state() helper is currently only called from > pci_walk_bus(), something which can lead to a deadlock as both helpers > take a pci_bus_sem read lock. > > Add a new locked helper which can be called with the read lock held and > fix up the two current users (the second is new in 6.7-rc1). > > Note that there are no users left of the original unlocked variant after > this series, but I decided to leave it in place for now (e.g. to mirror > the corresponding helpers to disable link states). > > Included are also a couple of related cleanups. > > Johan > > > Changes in v2 > - fix up the function name in a kernel doc comment as reported by the > kernel test robot <lkp@intel.com> > > > Johan Hovold (6): > PCI/ASPM: Add locked helper for enabling link state > PCI: vmd: Fix deadlock when enabling ASPM > PCI: qcom: Fix deadlock when enabling ASPM > PCI: qcom: Clean up ASPM comment > PCI/ASPM: Clean up disable link state parameter > PCI/ASPM: Add lockdep assert to link state helper > > drivers/pci/controller/dwc/pcie-qcom.c | 7 ++- > drivers/pci/controller/vmd.c | 2 +- > drivers/pci/pcie/aspm.c | 65 +++++++++++++++++++------- > include/linux/pci.h | 3 ++ > 4 files changed, 56 insertions(+), 21 deletions(-) Applied to for-linus for v6.7, thanks, Johan!
[TLDR: This mail in primarily relevant for Linux kernel regression tracking. See link in footer if these mails annoy you.] On 07.12.23 14:25, Johan Hovold wrote: > On Tue, Nov 28, 2023 at 09:15:06AM +0100, Johan Hovold wrote: >> The pci_enable_link_state() helper is currently only called from >> pci_walk_bus(), something which can lead to a deadlock as both helpers >> take a pci_bus_sem read lock. >> >> Add a new locked helper which can be called with the read lock held and >> fix up the two current users (the second is new in 6.7-rc1). >> >> Note that there are no users left of the original unlocked variant after >> this series, but I decided to leave it in place for now (e.g. to mirror >> the corresponding helpers to disable link states). >> >> Included are also a couple of related cleanups. > >> Johan Hovold (6): >> PCI/ASPM: Add locked helper for enabling link state >> PCI: vmd: Fix deadlock when enabling ASPM >> PCI: qcom: Fix deadlock when enabling ASPM >> PCI: qcom: Clean up ASPM comment >> PCI/ASPM: Clean up disable link state parameter >> PCI/ASPM: Add lockdep assert to link state helper > > Could we get this merged for 6.7-rc5? Even if the risk of a deadlock is > not that great, this bug prevents using lockdep on Qualcomm platforms so > that more locking issues can potentially make their way into the kernel. > > And for Qualcomm platforms, this is a regression in 6.7-rc1. > > #regzbot introduced: 9f4f3dfad8cf Fixes are now here: https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/log/?h=for-linus #regzbot fix: 075268be58232b0a2ae #regzbot ignore-activity Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat) -- Everything you wanna know about Linux kernel regression tracking: https://linux-regtracking.leemhuis.info/about/#tldr That page also explains what to do if mails like this annoy you.
Hi Bjorn, On Fri, Dec 08, 2023 at 11:53:12AM -0600, Bjorn Helgaas wrote: > On Tue, Nov 28, 2023 at 09:15:06AM +0100, Johan Hovold wrote: > > Johan Hovold (6): > > PCI/ASPM: Add locked helper for enabling link state > > PCI: vmd: Fix deadlock when enabling ASPM > > PCI: qcom: Fix deadlock when enabling ASPM > > PCI: qcom: Clean up ASPM comment > > PCI/ASPM: Clean up disable link state parameter > > PCI/ASPM: Add lockdep assert to link state helper > Applied to for-linus for v6.7, thanks, Johan! I've noticed that you're pretty keen on amending commit messages. For this series, for example, I noticed that you added an American comma after "e.g." even though this is not expected in British English that I (try to) use. This risks introducing inconsistencies and frankly I see no reason for this kind of editing. British English is not an error. :) You also added a plus sign after the stable kernel versions in the comments after the CC-stable tags even though this is not the right notation for this (see the stable kernel rules). I'm more OK with you preferring to use function names over free text in commit messages even if that is not my preferred style. But generally I find it a bit odd that you insist on rewriting commit messages like this and would prefer if you did not (especially since there's no record of you having done this in the commits themselves). Fixing typos and grammar issues, or rewriting bad commit messages, is another thing of course. Johan
On Mon, Dec 11, 2023 at 06:35:46PM +0100, Johan Hovold wrote: > Hi Bjorn, > > On Fri, Dec 08, 2023 at 11:53:12AM -0600, Bjorn Helgaas wrote: > > On Tue, Nov 28, 2023 at 09:15:06AM +0100, Johan Hovold wrote: > > > > Johan Hovold (6): > > > PCI/ASPM: Add locked helper for enabling link state > > > PCI: vmd: Fix deadlock when enabling ASPM > > > PCI: qcom: Fix deadlock when enabling ASPM > > > PCI: qcom: Clean up ASPM comment > > > PCI/ASPM: Clean up disable link state parameter > > > PCI/ASPM: Add lockdep assert to link state helper > > > Applied to for-linus for v6.7, thanks, Johan! > > I've noticed that you're pretty keen on amending commit messages. > > For this series, for example, I noticed that you added an American comma > after "e.g." even though this is not expected in British English that I > (try to) use. This risks introducing inconsistencies and frankly I see no > reason for this kind of editing. British English is not an error. :) > > You also added a plus sign after the stable kernel versions in the > comments after the CC-stable tags even though this is not the right > notation for this (see the stable kernel rules). Fixed, sorry.
On Mon, Dec 11, 2023 at 12:11:53PM -0600, Bjorn Helgaas wrote: > On Mon, Dec 11, 2023 at 06:35:46PM +0100, Johan Hovold wrote: > > I've noticed that you're pretty keen on amending commit messages. > > > > For this series, for example, I noticed that you added an American comma > > after "e.g." even though this is not expected in British English that I > > (try to) use. This risks introducing inconsistencies and frankly I see no > > reason for this kind of editing. British English is not an error. :) > > > > You also added a plus sign after the stable kernel versions in the > > comments after the CC-stable tags even though this is not the right > > notation for this (see the stable kernel rules). > > Fixed, sorry. Thanks! Johan