FireAsf 🔥
2331979d71
[ Upstream commit 6841cab8c4504835e4011689cbdb3351dec693fd ]
This race condition was discovered while updating the at91_can driver
to use can_bus_off(). The following scenario describes how the
converted at91_can driver would behave.
When a CAN device goes into BUS-OFF state, the driver usually
stops/resets the CAN device and calls can_bus_off().
This function sets the netif carrier to off, and (if configured by
user space) schedules a delayed work that calls can_restart() to
restart the CAN device.
The can_restart() function first checks if the carrier is off and
triggers an error message if the carrier is OK.
Then it calls the driver's do_set_mode() function to restart the
device, then it sets the netif carrier to on. There is a race window
between these two calls.
The at91 CAN controller (observed on the sama5d3, a single core 32 bit
ARM CPU) has a hardware limitation. If the device goes into bus-off
while sending a CAN frame, there is no way to abort the sending of
this frame. After the controller is enabled again, another attempt is
made to send it.
If the bus is still faulty, the device immediately goes back to the
bus-off state. The driver calls can_bus_off(), the netif carrier is
switched off and another can_restart is scheduled. This occurs within
the race window before the original can_restart() handler marks the
netif carrier as OK. This would cause the 2nd can_restart() to be
called with an OK netif carrier, resulting in an error message.
The flow of the 1st can_restart() looks like this:
can_restart()
// bail out if netif_carrier is OK
netif_carrier_ok(dev)
priv->do_set_mode(dev, CAN_MODE_START)
// enable CAN controller
// sama5d3 restarts sending old message
// CAN devices goes into BUS_OFF, triggers IRQ
// IRQ handler start
at91_irq()
at91_irq_err_line()
can_bus_off()
netif_carrier_off()
schedule_delayed_work()
// IRQ handler end
netif_carrier_on()
The 2nd can_restart() will be called with an OK netif carrier and the
error message will be printed.
To close the race window, first set the netif carrier to on, then
restart the controller. In case the restart fails with an error code,
roll back the netif carrier to off.
Fixes: 39549eef3587 ("can: CAN Network device driver and Netlink interface")
Link: https://lore.kernel.org/all/20231005-can-dev-fix-can-restart-v2-2-91b5c1fd922c@pengutronix.de
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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| android | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware/tsp_goodix | ||
| fs | ||
| gki | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| kernel_build | ||
| kunitconfigs | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| test | ||
| tools | ||
| usr | ||
| virt | ||
| build.config.aarch64 | ||
| build.config.allmodconfig | ||
| build.config.allmodconfig.aarch64 | ||
| build.config.allmodconfig.arm | ||
| build.config.allmodconfig.x86_64 | ||
| build.config.amlogic | ||
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| build.config.common | ||
| build.config.db845c | ||
| build.config.erd8825_a25_s | ||
| build.config.erd8825_s | ||
| build.config.erd9925_evt0_s | ||
| build.config.erd9925_evt0_s5300_s | ||
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| build.config.gki-debug.aarch64 | ||
| build.config.gki-debug.x86_64 | ||
| build.config.gki.aarch64 | ||
| build.config.gki.aarch64.fips140 | ||
| build.config.gki.aarch64.fips140_eval_testing | ||
| build.config.gki.x86_64 | ||
| build.config.gki_kasan | ||
| build.config.gki_kasan.aarch64 | ||
| build.config.gki_kasan.x86_64 | ||
| build.config.gki_kprobes | ||
| build.config.gki_kprobes.aarch64 | ||
| build.config.gki_kprobes.x86_64 | ||
| build.config.hikey960 | ||
| build.config.khwasan | ||
| build.config.mcd | ||
| build.config.rockchip | ||
| build.config.universal2100_s | ||
| build.config.universal8825_s | ||
| build.config.universal9925_evt0_s | ||
| build.config.universal9925_s | ||
| build.config.x86_64 | ||
| build.sh | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| linux-stable.sh | ||
| MAINTAINERS | ||
| Makefile | ||
| OWNERS | ||
| README | ||
| README.md | ||
| vendor_boot_module_order_exynos2100.cfg | ||
| vendor_boot_module_order_s5e8825.cfg | ||
| vendor_boot_module_order_s5e9925.cfg | ||
| vendor_module_list_s5e8825.cfg | ||
| vendor_module_list_s5e9925.cfg | ||
| vendor_module_list_s5e9925_b0s.cfg | ||
| vendor_module_list_s5e9925_g0s.cfg | ||
| vendor_module_list_s5e9925_r0s.cfg | ||
How do I submit patches to Android Common Kernels
-
BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.
- Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux,
additions of
EXPORT_SYMBOL_GPL()require an in-tree modular driver that uses the symbol -- so include the new driver or changes to an existing driver in the same patchset as the export. - When sending patches upstream, the commit message must contain a clear case for why the patch is needed and beneficial to the community. Enabling out-of-tree drivers or functionality is not not a persuasive case.
- Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux,
additions of
-
LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.
Common Kernel patch requirements
- All patches must conform to the Linux kernel coding standards and pass
script/checkpatch.pl - Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
- If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch:
UPSTREAM:,BACKPORT:,FROMGIT:,FROMLIST:, orANDROID:. - All patches must have a
Change-Id:tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html) - If an Android bug has been assigned, there must be a
Bug:tag. - All patches must have a
Signed-off-by:tag by the author and the submitter
Additional requirements are listed below based on patch type
Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:
- If the patch is a cherry-pick from Linux mainline with no changes at all
- tag the patch subject with
UPSTREAM:. - add upstream commit information with a
(cherry picked from commit ...)line - Example:
- if the upstream commit message is
- tag the patch subject with
important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
- then Joe Smith would upload the patch for the common kernel as
UPSTREAM: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
(cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
Signed-off-by: Joe Smith <joe.smith@foo.org>
- If the patch requires any changes from the upstream version, tag the patch with
BACKPORT:instead ofUPSTREAM:.- use the same tags as
UPSTREAM: - add comments about the changes under the
(cherry picked from commit ...)line - Example:
- use the same tags as
BACKPORT: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
(cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
[joe: Resolved minor conflict in drivers/foo/bar.c ]
Signed-off-by: Joe Smith <joe.smith@foo.org>
Requirements for other backports: FROMGIT:, FROMLIST:,
- If the patch has been merged into an upstream maintainer tree, but has not yet
been merged into Linux mainline
- tag the patch subject with
FROMGIT: - add info on where the patch came from as
(cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't uselinux-nextfor example). - if changes were required, use
BACKPORT: FROMGIT: - Example:
- if the commit message in the maintainer tree is
- tag the patch subject with
important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
- then Joe Smith would upload the patch for the common kernel as
FROMGIT: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
(cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
Signed-off-by: Joe Smith <joe.smith@foo.org>
- If the patch has been submitted to LKML, but not accepted into any maintainer tree
- tag the patch subject with
FROMLIST: - add a
Link:tag with a link to the submittal on lore.kernel.org - add a
Bug:tag with the Android bug (required for patches not accepted into a maintainer tree) - if changes were required, use
BACKPORT: FROMLIST: - Example:
- tag the patch subject with
FROMLIST: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
Signed-off-by: Joe Smith <joe.smith@foo.org>
Requirements for Android-specific patches: ANDROID:
- If the patch is fixing a bug to Android-specific code
- tag the patch subject with
ANDROID: - add a
Fixes:tag that cites the patch with the bug - Example:
- tag the patch subject with
ANDROID: fix android-specific bug in foobar.c
This is the detailed description of the important fix
Fixes: 1234abcd2468 ("foobar: add cool feature")
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
Signed-off-by: Joe Smith <joe.smith@foo.org>
- If the patch is a new feature
- tag the patch subject with
ANDROID: - add a
Bug:tag with the Android bug (required for android-specific features)
- tag the patch subject with