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We get a report that a wireless ethernet device which uses legacy interrupt, exposes a buggy behaviour when patching RT support. It can be observed on RK3588 EVB1 with NVMe under RT environment when adding pci=nomsi to cmdline. The backtrace looks like below: echo 3 > /proc/sys/vm/drop_caches && dd if=/dev/nvme0n1 of=/dev/null bs=1M count=50000 [ 10.826850] irq 155: nobody cared (try booting with the "irqpoll" option) [ 10.826862] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.10.160-rt89 #505 [ 10.826867] Hardware name: Rockchip RK3588 EVB1 LP4 V10 Board (DT) [ 10.826870] Call trace: [ 10.826871] dump_backtrace+0x0/0x1e0 [ 10.826881] show_stack+0x18/0x24 [ 10.826886] dump_stack_lvl+0xcc/0xf8 [ 10.826891] dump_stack+0x18/0x54 [ 10.826895] __report_bad_irq+0x4c/0xdc [ 10.826899] note_interrupt+0x2cc/0x380 [ 10.826905] handle_irq_event+0x10c/0x180 [ 10.826909] handle_simple_irq+0xac/0x120 [ 10.826913] generic_handle_irq+0x30/0x50 [ 10.826917] rk_pcie_legacy_int_handler+0xa8/0x160 [ 10.826923] __handle_domain_irq+0xb8/0x140 [ 10.826927] gic_handle_irq+0xd8/0x2e4 [ 10.826932] el1_irq+0xcc/0x180 [ 10.826935] arch_cpu_idle+0x18/0x3c [ 10.826940] default_idle_call+0x2c/0x9c [ 10.826944] do_idle+0x21c/0x2a0 [ 10.826949] cpu_startup_entry+0x24/0x70 [ 10.826952] rest_init+0xd0/0xe0 [ 10.826956] arch_call_rest_init+0x10/0x1c [ 10.826960] start_kernel+0x50c/0x544 [ 10.826963] handlers: [ 10.826965] [<0000000015317c1f>] irq_default_primary_handler threaded [<00000000edb1561e>] pcie_pme_irq [ 10.826977] [<0000000015317c1f>] irq_default_primary_handler threaded [<000000000065643b>] nvme_irq [ 10.826988] [<0000000015317c1f>] irq_default_primary_handler threaded [<000000000065643b>] nvme_irq [ 10.826996] Disabling IRQ #155 And NVMe can't work anymore due to the irq problem. The actual problem looks like: nvme_irq nvme_irq //process the previous request -> nvme_process_cq(nvmeq) // the previous one is still processing -> if(nvme_process_cq(nvmeq)) -> return IRQ_HANDLED -> return IRQ_NONE so a spurious irq was counted and if the irq ack time is short enough to increase the spurious irq exceeding the limitation, report_bad_irq was triggered. This is why the bug was only observed under RT environment since the irq was distributed more quickly than ever, but the bug was always there. root@linaro-alip:/# cat /proc/irq/155/spurious count 8990 unhandled 24339 last_unhandled 189829 ms This can be fixed by the drivers as we could see many patches regarding "irq xxx: nobody cared", and it's the case if we don't allow nvme_irq to nest itself or postpone the handler. However the legacy interrupt support is also buggy. For legacy interrupt, it's a level irq rather than an edge one. But it happened to work because Rockchip PCIe RC only generates oneshot irq instead of level, preventing the irq storm from happening. So changing to use handle_level_irq is correct and should help mask/unmask the irq when dealing with it in between. That's a decent solution for all. Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> Change-Id: Ie9499b3dbd19ac053500b4c726294296be537ffd
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