lkml.org 
[lkml]   [2018]   [Mar]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.14 063/140] drm/nouveau: Fix deadlock on runtime suspend
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Lukas Wunner <lukas@wunner.de>

    commit d61a5c1063515e855bedb1b81e20e50b0ac3541e upstream.

    nouveau's ->runtime_suspend hook calls drm_kms_helper_poll_disable(),
    which waits for the output poll worker to finish if it's running.

    The output poll worker meanwhile calls pm_runtime_get_sync() in
    nouveau_connector_detect() which waits for the ongoing suspend to finish,
    causing a deadlock.

    Fix by not acquiring a runtime PM ref if nouveau_connector_detect() is
    called in the output poll worker's context. This is safe because
    the poll worker is only enabled while runtime active and we know that
    ->runtime_suspend waits for it to finish.

    Other contexts calling nouveau_connector_detect() do require a runtime
    PM ref, these comprise:

    status_store() drm sysfs interface
    ->fill_modes drm callback
    drm_fb_helper_probe_connector_modes()
    drm_mode_getconnector()
    nouveau_connector_hotplug()
    nouveau_display_hpd_work()
    nv17_tv_set_property()

    Stack trace for posterity:

    INFO: task kworker/0:1:58 blocked for more than 120 seconds.
    Workqueue: events output_poll_execute [drm_kms_helper]
    Call Trace:
    schedule+0x28/0x80
    rpm_resume+0x107/0x6e0
    __pm_runtime_resume+0x47/0x70
    nouveau_connector_detect+0x7e/0x4a0 [nouveau]
    nouveau_connector_detect_lvds+0x132/0x180 [nouveau]
    drm_helper_probe_detect_ctx+0x85/0xd0 [drm_kms_helper]
    output_poll_execute+0x11e/0x1c0 [drm_kms_helper]
    process_one_work+0x184/0x380
    worker_thread+0x2e/0x390

    INFO: task kworker/0:2:252 blocked for more than 120 seconds.
    Workqueue: pm pm_runtime_work
    Call Trace:
    schedule+0x28/0x80
    schedule_timeout+0x1e3/0x370
    wait_for_completion+0x123/0x190
    flush_work+0x142/0x1c0
    nouveau_pmops_runtime_suspend+0x7e/0xd0 [nouveau]
    pci_pm_runtime_suspend+0x5c/0x180
    vga_switcheroo_runtime_suspend+0x1e/0xa0
    __rpm_callback+0xc1/0x200
    rpm_callback+0x1f/0x70
    rpm_suspend+0x13c/0x640
    pm_runtime_work+0x6e/0x90
    process_one_work+0x184/0x380
    worker_thread+0x2e/0x390

    Bugzilla: https://bugs.archlinux.org/task/53497
    Bugzilla: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=870523
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=70388#c33
    Fixes: 5addcf0a5f0f ("nouveau: add runtime PM support (v0.9)")
    Cc: stable@vger.kernel.org # v3.12+: 27d4ee03078a: workqueue: Allow retrieval of current task's work struct
    Cc: stable@vger.kernel.org # v3.12+: 25c058ccaf2e: drm: Allow determining if current task is output poll worker
    Cc: Ben Skeggs <bskeggs@redhat.com>
    Cc: Dave Airlie <airlied@redhat.com>
    Reviewed-by: Lyude Paul <lyude@redhat.com>
    Signed-off-by: Lukas Wunner <lukas@wunner.de>
    Link: https://patchwork.freedesktop.org/patch/msgid/b7d2cbb609a80f59ccabfdf479b9d5907c603ea1.1518338789.git.lukas@wunner.de
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/gpu/drm/nouveau/nouveau_connector.c | 18 +++++++++++++-----
    1 file changed, 13 insertions(+), 5 deletions(-)

    --- a/drivers/gpu/drm/nouveau/nouveau_connector.c
    +++ b/drivers/gpu/drm/nouveau/nouveau_connector.c
    @@ -570,9 +570,15 @@ nouveau_connector_detect(struct drm_conn
    nv_connector->edid = NULL;
    }

    - ret = pm_runtime_get_sync(connector->dev->dev);
    - if (ret < 0 && ret != -EACCES)
    - return conn_status;
    + /* Outputs are only polled while runtime active, so acquiring a
    + * runtime PM ref here is unnecessary (and would deadlock upon
    + * runtime suspend because it waits for polling to finish).
    + */
    + if (!drm_kms_helper_is_poll_worker()) {
    + ret = pm_runtime_get_sync(connector->dev->dev);
    + if (ret < 0 && ret != -EACCES)
    + return conn_status;
    + }

    nv_encoder = nouveau_connector_ddc_detect(connector);
    if (nv_encoder && (i2c = nv_encoder->i2c) != NULL) {
    @@ -647,8 +653,10 @@ detect_analog:

    out:

    - pm_runtime_mark_last_busy(connector->dev->dev);
    - pm_runtime_put_autosuspend(connector->dev->dev);
    + if (!drm_kms_helper_is_poll_worker()) {
    + pm_runtime_mark_last_busy(connector->dev->dev);
    + pm_runtime_put_autosuspend(connector->dev->dev);
    + }

    return conn_status;
    }

    \
     
     \ /
      Last update: 2018-03-13 16:59    [W:2.160 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site