Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Bryan O'Donoghue <bryan.odonoghue@linaro.org>
To:     rfoss@kernel.org, todor.too@gmail.com, bryan.odonoghue@linaro.org,
        agross@kernel.org, andersson@kernel.org, konrad.dybcio@linaro.org,
        mchehab@kernel.org, hverkuil-cisco@xs4all.nl,
        sakari.ailus@linux.intel.com, andrey.konovalov@linaro.org
Cc:     linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: [PATCH v0 3/9] media: qcom: camss: Fix vfe_get() error jump
Date:   Mon, 14 Aug 2023 15:10:01 +0100
Message-ID: <20230814141007.3721197-4-bryan.odonoghue@linaro.org>
In-Reply-To: <20230814141007.3721197-1-bryan.odonoghue@linaro.org>
References: <20230814141007.3721197-1-bryan.odonoghue@linaro.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Right now it is possible to do a vfe_get() with the internal reference
count at 1. If vfe_check_clock_rates() returns non-zero then we will
leave the reference count as-is and

run:
- pm_runtime_put_sync()
- vfe->ops->pm_domain_off()

skip:
- camss_disable_clocks()

Subsequent vfe_put() calls will when the ref-count is non-zero
unconditionally run:

- pm_runtime_put_sync()
- vfe->ops->pm_domain_off()
- camss_disable_clocks()

vfe_get() should not attempt to roll-back on error when the ref-count is
non-zero as the upper layers will still do their own vfe_put() operations.

vfe_put() will drop the reference count and do the necessary power
domain release, the cleanup jumps in vfe_get() should only be run when
the ref-count is zero.

[   50.095796] CPU: 7 PID: 3075 Comm: cam Not tainted 6.3.2+ #80
[   50.095798] Hardware name: LENOVO 21BXCTO1WW/21BXCTO1WW, BIOS N3HET82W (1.54 ) 05/26/2023
[   50.095799] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[   50.095802] pc : refcount_warn_saturate+0xf4/0x148
[   50.095804] lr : refcount_warn_saturate+0xf4/0x148
[   50.095805] sp : ffff80000c7cb8b0
[   50.095806] x29: ffff80000c7cb8b0 x28: ffff16ecc0e3fc10 x27: 0000000000000000
[   50.095810] x26: 0000000000000000 x25: 0000000000020802 x24: 0000000000000000
[   50.095813] x23: ffff16ecc7360640 x22: 00000000ffffffff x21: 0000000000000005
[   50.095815] x20: ffff16ed175f4400 x19: ffffb4d9852942a8 x18: ffffffffffffffff
[   50.095818] x17: ffffb4d9852d4a48 x16: ffffb4d983da5db8 x15: ffff80000c7cb320
[   50.095821] x14: 0000000000000001 x13: 2e656572662d7265 x12: 7466612d65737520
[   50.095823] x11: 00000000ffffefff x10: ffffb4d9850cebf0 x9 : ffffb4d9835cf954
[   50.095826] x8 : 0000000000017fe8 x7 : c0000000ffffefff x6 : 0000000000057fa8
[   50.095829] x5 : ffff16f813fe3d08 x4 : 0000000000000000 x3 : ffff621e8f4d2000
[   50.095832] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff16ed32119040
[   50.095835] Call trace:
[   50.095836]  refcount_warn_saturate+0xf4/0x148
[   50.095838]  device_link_put_kref+0x84/0xc8
[   50.095843]  device_link_del+0x38/0x58
[   50.095846]  vfe_pm_domain_off+0x3c/0x50 [qcom_camss]
[   50.095860]  vfe_put+0x114/0x140 [qcom_camss]
[   50.095869]  csid_set_power+0x2c8/0x408 [qcom_camss]
[   50.095878]  pipeline_pm_power_one+0x164/0x170 [videodev]
[   50.095896]  pipeline_pm_power+0xc4/0x110 [videodev]
[   50.095909]  v4l2_pipeline_pm_use+0x5c/0xa0 [videodev]
[   50.095923]  v4l2_pipeline_pm_get+0x1c/0x30 [videodev]
[   50.095937]  video_open+0x7c/0x100 [qcom_camss]
[   50.095945]  v4l2_open+0x84/0x130 [videodev]
[   50.095960]  chrdev_open+0xc8/0x250
[   50.095964]  do_dentry_open+0x1bc/0x498
[   50.095966]  vfs_open+0x34/0x40
[   50.095968]  path_openat+0xb44/0xf20
[   50.095971]  do_filp_open+0xa4/0x160
[   50.095974]  do_sys_openat2+0xc8/0x188
[   50.095975]  __arm64_sys_openat+0x6c/0xb8
[   50.095977]  invoke_syscall+0x50/0x128
[   50.095982]  el0_svc_common.constprop.0+0x4c/0x100
[   50.095985]  do_el0_svc+0x40/0xa8
[   50.095988]  el0_svc+0x2c/0x88
[   50.095991]  el0t_64_sync_handler+0xf4/0x120
[   50.095994]  el0t_64_sync+0x190/0x198
[   50.095996] ---[ end trace 0000000000000000 ]---

Fixes: 779096916dae ("media: camss: vfe: Fix runtime PM imbalance on error")
Cc: stable@vger.kernel.org
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
---
 drivers/media/platform/qcom/camss/camss-vfe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/platform/qcom/camss/camss-vfe.c b/drivers/media/platform/qcom/camss/camss-vfe.c
index dabfd613b2f94..938f373bcd1fd 100644
--- a/drivers/media/platform/qcom/camss/camss-vfe.c
+++ b/drivers/media/platform/qcom/camss/camss-vfe.c
@@ -611,7 +611,7 @@ int vfe_get(struct vfe_device *vfe)
 	} else {
 		ret = vfe_check_clock_rates(vfe);
 		if (ret < 0)
-			goto error_pm_runtime_get;
+			goto error_pm_domain;
 	}
 	vfe->power_count++;
 
-- 
2.41.0