linux.git/drivers/net/ipa/ipa_modem.c, branch v7.3-rc2 Linux kernel source tree net: ipa: fix stalled modem TX queue after runtime resume 2026-08-20T18:33:39+00:00 Jorijn van der Graaf jorijnvdgraaf@catcrafts.net 2026-08-15T04:03:02+00:00 3cbfd627ee720f3d2460d2cbe2fe9e4130240db6 ipa_start_xmit() unconditionally stops the TX queue before calling pm_runtime_get(), relying on the wake scheduled by runtime resume (ipa_modem_wake_queue_work()) to restart it once power is ACTIVE. But that work is queued from within the runtime resume callback, before the device's power state reaches RPM_ACTIVE, so it can run while the device is still RPM_RESUMING. The wake is then consumed too early: the transmit it restarts stops the queue again, pm_runtime_get() returns -EINPROGRESS without arranging any future wake (deferred_resume exists only for RPM_SUSPENDING), and after the resume completes nothing is left to wake the queue. Transmit stalls permanently: packets pile up in the qdisc behind the stopped queue, the device runtime-suspends, and since the netdev registers no ndo_tx_timeout the watchdog never fires. Observed on SM7635 (Fairphone 6) as the cellular data path going permanently deaf within hours, RX included, since nothing resumes the suspended endpoints. Close the window by making the wake work wait for the resume to complete (pm_runtime_get_sync()) before waking the queue. Every queue stop is then guaranteed a later wake that happens while power is ACTIVE; a transmit racing a new suspend/resume cycle re-schedules the work. If the device could not be resumed, wake the queue anyway so pending packets are dropped by the transmit path rather than stranded. The STARTED power flag used to narrow this window: a wake running before the transmit path's stop suppressed that stop, but only once, as the flag was cleared by the first stop it absorbed. Removing the flag made a single transmit during an in-flight resume sufficient to strand the queue, which is the form observed. With an accelerated reproducer (autosuspend delay shortened to 5 ms, ~20 packets/s of TX), an unpatched kernel stalled three times in 230 s / 4380 packets; with this patch the same test ran 3601 s / 70298 packets without a stall. Fixes: 688de12f080f ("net: ipa: kill the STARTED IPA power flag") Cc: stable@vger.kernel.org Signed-off-by: Jorijn van der Graaf <jorijnvdgraaf@catcrafts.net> Reviewed-by: Simon Horman <horms@kernel.org> Link: https://patch.msgid.link/20260815040302.653650-1-jorijnvdgraaf@catcrafts.net Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
ipa_start_xmit() unconditionally stops the TX queue before calling
pm_runtime_get(), relying on the wake scheduled by runtime resume
(ipa_modem_wake_queue_work()) to restart it once power is ACTIVE.
But that work is queued from within the runtime resume callback,
before the device's power state reaches RPM_ACTIVE, so it can run
while the device is still RPM_RESUMING.  The wake is then consumed
too early: the transmit it restarts stops the queue again,
pm_runtime_get() returns -EINPROGRESS without arranging any future
wake (deferred_resume exists only for RPM_SUSPENDING), and after the
resume completes nothing is left to wake the queue.  Transmit stalls
permanently: packets pile up in the qdisc behind the stopped queue,
the device runtime-suspends, and since the netdev registers no
ndo_tx_timeout the watchdog never fires.  Observed on SM7635
(Fairphone 6) as the cellular data path going permanently deaf
within hours, RX included, since nothing resumes the suspended
endpoints.

Close the window by making the wake work wait for the resume to
complete (pm_runtime_get_sync()) before waking the queue.  Every
queue stop is then guaranteed a later wake that happens while power
is ACTIVE; a transmit racing a new suspend/resume cycle re-schedules
the work.  If the device could not be resumed, wake the queue anyway
so pending packets are dropped by the transmit path rather than
stranded.

The STARTED power flag used to narrow this window: a wake running
before the transmit path's stop suppressed that stop, but only once,
as the flag was cleared by the first stop it absorbed.  Removing the
flag made a single transmit during an in-flight resume sufficient to
strand the queue, which is the form observed.

With an accelerated reproducer (autosuspend delay shortened to 5 ms,
~20 packets/s of TX), an unpatched kernel stalled three times in
230 s / 4380 packets; with this patch the same test ran 3601 s /
70298 packets without a stall.

Fixes: 688de12f080f ("net: ipa: kill the STARTED IPA power flag")
Cc: stable@vger.kernel.org
Signed-off-by: Jorijn van der Graaf <jorijnvdgraaf@catcrafts.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20260815040302.653650-1-jorijnvdgraaf@catcrafts.net
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: ipa: Remove redundant pm_runtime_mark_last_busy() calls 2025-10-30T01:55:56+00:00 Sakari Ailus sakari.ailus@linux.intel.com 2025-10-27T11:50:20+00:00 a5d937dd0ead5ff826f94eb926f26106b6d178fa pm_runtime_put_autosuspend(), pm_runtime_put_sync_autosuspend(), pm_runtime_autosuspend() and pm_request_autosuspend() now include a call to pm_runtime_mark_last_busy(). Remove the now-reduntant explicit call to pm_runtime_mark_last_busy(). Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com> Link: https://patch.msgid.link/20251027115022.390997-2-sakari.ailus@linux.intel.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
pm_runtime_put_autosuspend(), pm_runtime_put_sync_autosuspend(),
pm_runtime_autosuspend() and pm_request_autosuspend() now include a call
to pm_runtime_mark_last_busy(). Remove the now-reduntant explicit call to
pm_runtime_mark_last_busy().

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Link: https://patch.msgid.link/20251027115022.390997-2-sakari.ailus@linux.intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: ipa: sort all includes 2024-04-18T11:01:05+00:00 Alex Elder elder@linaro.org 2024-04-16T23:10:18+00:00 884122775e675985c25702c2da8c8150a764a6c8 Establish the rule that header files are always included in sorted (POSIX local) order. Standard and private headers are separated by a blank line. Similarly, sort all forward-declarations for structures. Signed-off-by: Alex Elder <elder@linaro.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> 
Establish the rule that header files are always included in sorted
(POSIX local) order.  Standard and private headers are separated by
a blank line.

Similarly, sort all forward-declarations for structures.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
net: ipa: more include file cleanup 2024-04-18T11:01:05+00:00 Alex Elder elder@linaro.org 2024-04-16T23:10:17+00:00 f60e5fb6dfafef0bcf32b4bc7f4fc2f5f1285815 All of the config data files and all of the register definition files (plus a few others) use GSI_EE_AP, which is defined in "ipa_version.h". Include that header where it's needed. All of the IPA register definition files include "../ipa.h", though none of them need anything defined there. Similarly, all of the GSI register definition files include "../gsi.h", but don't need anything defined there. Remove these unnneded includes. All of the configuration data files include "../gsi.h", though none of them need anything defined there, so remove these includes. Remove other includes of local header files that are not required. Signed-off-by: Alex Elder <elder@linaro.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> 
All of the config data files and all of the register definition
files (plus a few others) use GSI_EE_AP, which is defined in
"ipa_version.h".  Include that header where it's needed.

All of the IPA register definition files include "../ipa.h", though
none of them need anything defined there.  Similarly, all of the GSI
register definition files include "../gsi.h", but don't need anything
defined there.  Remove these unnneded includes.

All of the configuration data files include "../gsi.h", though none
of them need anything defined there, so remove these includes.

Remove other includes of local header files that are not required.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
net: ipa: don't save the platform device 2024-03-04T11:44:41+00:00 Alex Elder elder@linaro.org 2024-03-01T17:02:42+00:00 5245f4fd28d126cc13e32e77abc8a8fd287167b0 The IPA platform device is now only used as the structure containing the IPA device structure. Replace the platform device pointer with a pointer to the device structure. Signed-off-by: Alex Elder <elder@linaro.org> Signed-off-by: David S. Miller <davem@davemloft.net> 
The IPA platform device is now only used as the structure containing
the IPA device structure.  Replace the platform device pointer with
a pointer to the device structure.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: ipa: kill ipa_power_modem_queue_wake() 2024-02-02T04:50:36+00:00 Alex Elder elder@linaro.org 2024-01-30T19:23:04+00:00 e01bbdc9f8513395a8554aeeeef8f45dd26dfe15 All ipa_power_modem_queue_wake() does is call netif_wake_queue() on the modem netdev. There is no need to wrap that call in a trivial function (and certainly not one defined in "ipa_power.c"). So get rid of ipa_power_modem_queue_wake(), and replace its one caller with a direct call to netif_wake_queue(). Determine the netdev pointer to use from the private TX endpoint's netdev pointer. Signed-off-by: Alex Elder <elder@linaro.org> Link: https://lore.kernel.org/r/20240130192305.250915-8-elder@linaro.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
All ipa_power_modem_queue_wake() does is call netif_wake_queue()
on the modem netdev.  There is no need to wrap that call in a
trivial function (and certainly not one defined in "ipa_power.c").

So get rid of ipa_power_modem_queue_wake(), and replace its one
caller with a direct call to netif_wake_queue().  Determine the
netdev pointer to use from the private TX endpoint's netdev pointer.

Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20240130192305.250915-8-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: ipa: kill ipa_power_modem_queue_active() 2024-02-02T04:50:36+00:00 Alex Elder elder@linaro.org 2024-01-30T19:23:03+00:00 2acf5fc8dabaf9a5b14a678cd039f974dc749768 All ipa_power_modem_queue_active() does now is call netif_wake_queue(). Just call netif_wake_queue() in the two places it's needed, and get rid of ipa_power_modem_queue_active(). Signed-off-by: Alex Elder <elder@linaro.org> Link: https://lore.kernel.org/r/20240130192305.250915-7-elder@linaro.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
All ipa_power_modem_queue_active() does now is call netif_wake_queue().
Just call netif_wake_queue() in the two places it's needed, and get
rid of ipa_power_modem_queue_active().

Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20240130192305.250915-7-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: ipa: kill ipa_power_modem_queue_stop() 2024-02-02T04:50:36+00:00 Alex Elder elder@linaro.org 2024-01-30T19:23:02+00:00 30cdaea236009c6f626f0660ac4ca08558a2166f All ipa_power_modem_queue_stop() does now is call netif_stop_queue(). Just call netif_stop_queue() in the one place it's needed, and get rid of ipa_power_modem_queue_stop(). Signed-off-by: Alex Elder <elder@linaro.org> Link: https://lore.kernel.org/r/20240130192305.250915-6-elder@linaro.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
All ipa_power_modem_queue_stop() does now is call netif_stop_queue().
Just call netif_stop_queue() in the one place it's needed, and get
rid of ipa_power_modem_queue_stop().

Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20240130192305.250915-6-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: ipa: begin simplifying TX queue stop 2024-02-02T04:50:36+00:00 Alex Elder elder@linaro.org 2024-01-30T19:22:59+00:00 844ecc4aa78e2f291071025cf76a98287b38856a There are a number of flags used in the IPA driver to attempt to manage race conditions that can occur between runtime resume and netdev transmit. If we disable TX before requesting power, we can avoid these races entirely, simplifying things considerably. This patch implements the main change, disabling transmit always in the net_device->ndo_start_xmit() callback, then re-enabling it again whenever we find power is active (or when we drop the skb). The patches that follow will refactor the "old" code to the point that most of it can be eliminated. Signed-off-by: Alex Elder <elder@linaro.org> Link: https://lore.kernel.org/r/20240130192305.250915-3-elder@linaro.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
There are a number of flags used in the IPA driver to attempt to
manage race conditions that can occur between runtime resume and
netdev transmit.  If we disable TX before requesting power, we can
avoid these races entirely, simplifying things considerably.

This patch implements the main change, disabling transmit always in
the net_device->ndo_start_xmit() callback, then re-enabling it again
whenever we find power is active (or when we drop the skb).

The patches that follow will refactor the "old" code to the point
that most of it can be eliminated.

Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20240130192305.250915-3-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net: ipa: stash modem TX and RX endpoints 2024-02-02T04:50:35+00:00 Alex Elder elder@linaro.org 2024-01-30T19:22:58+00:00 102c28b83ddf021c9902dc59e6436278a0975916 Rather than repeatedly looking up the endpoints in the name map, save the modem TX and RX endpoint pointers in the netdev private area. Signed-off-by: Alex Elder <elder@linaro.org> Link: https://lore.kernel.org/r/20240130192305.250915-2-elder@linaro.org Signed-off-by: Jakub Kicinski <kuba@kernel.org> 
Rather than repeatedly looking up the endpoints in the name map,
save the modem TX and RX endpoint pointers in the netdev private
area.

Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20240130192305.250915-2-elder@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>