Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.4 22/31] drm/bridge: adv7511: Fix mutex deadlock when interrupts are disabled | Date | Tue, 12 Sep 2017 09:56:17 -0700 |
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4.4-stable review patch. If anyone has any objections, please let me know.
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From: Archit Taneja <architt@codeaurora.org>
commit f0bfcc22d9822947b0ad3095e8363eab5261864c upstream.
When the adv7511 i2c client doesn't have an interrupt line, we observe a deadlock on caused by trying to lock drm device's mode_config.mutex twice in the same context.
Here is the sequence that causes it:
ioctl DRM_IOCTL_MODE_GETCONNECTOR from userspace drm_mode_getconnector (acquires mode_config mutex) connector->fill_modes() drm_helper_probe_single_connector_modes connector_funcs->get_modes adv7511_encoder_get_modes adv7511_get_edid_block adv7511_irq_process drm_helper_hpd_irq_event (acquires mode_config mutex again)
In adv7511_irq_process, don't call drm_helper_hpd_irq_event when not called from the interrupt handler. It doesn't serve any purpose there anyway.
Signed-off-by: Archit Taneja <architt@codeaurora.org> Signed-off-by: Thong Ho <thong.ho.px@rvc.renesas.com> Signed-off-by: Nhan Nguyen <nhan.nguyen.yb@renesas.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/gpu/drm/i2c/adv7511.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/drivers/gpu/drm/i2c/adv7511.c +++ b/drivers/gpu/drm/i2c/adv7511.c @@ -429,7 +429,7 @@ static bool adv7511_hpd(struct adv7511 * return false; } -static int adv7511_irq_process(struct adv7511 *adv7511) +static int adv7511_irq_process(struct adv7511 *adv7511, bool process_hpd) { unsigned int irq0, irq1; int ret; @@ -445,7 +445,7 @@ static int adv7511_irq_process(struct ad regmap_write(adv7511->regmap, ADV7511_REG_INT(0), irq0); regmap_write(adv7511->regmap, ADV7511_REG_INT(1), irq1); - if (irq0 & ADV7511_INT0_HDP && adv7511->encoder) + if (process_hpd && irq0 & ADV7511_INT0_HDP && adv7511->encoder) drm_helper_hpd_irq_event(adv7511->encoder->dev); if (irq0 & ADV7511_INT0_EDID_READY || irq1 & ADV7511_INT1_DDC_ERROR) { @@ -463,7 +463,7 @@ static irqreturn_t adv7511_irq_handler(i struct adv7511 *adv7511 = devid; int ret; - ret = adv7511_irq_process(adv7511); + ret = adv7511_irq_process(adv7511, true); return ret < 0 ? IRQ_NONE : IRQ_HANDLED; } @@ -480,7 +480,7 @@ static int adv7511_wait_for_edid(struct adv7511->edid_read, msecs_to_jiffies(timeout)); } else { for (; timeout > 0; timeout -= 25) { - ret = adv7511_irq_process(adv7511); + ret = adv7511_irq_process(adv7511, false); if (ret < 0) break;
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