linux-kernel - [PATCH] scsi: ufs: core: Ensure clk_gating.lock is used only after initialization

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Message-Id: <20250122062718.3736823-1-avri.altman@wdc.com>
Date: Wed, 22 Jan 2025 08:27:18 +0200
From: Avri Altman <avri.altman@....com>
To: "Martin K . Petersen" <martin.petersen@...cle.com>
Cc: linux-scsi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Manivannan Sadhasivam <manisadhasivam.linux@...il.com>,
	Bart Van Assche <bvanassche@....org>,
	Avri Altman <avri.altman@....com>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Subject: [PATCH] scsi: ufs: core: Ensure clk_gating.lock is used only after initialization

This commit addresses a lockdep warning triggered by the use of the
clk_gating.lock before it is properly initialized. The warning is as
follows:

[    4.388838] INFO: trying to register non-static key.
[    4.395673] The code is fine but needs lockdep annotation, or maybe
[    4.402118] you didn't initialize this object before use?
[    4.407673] turning off the locking correctness validator.
[    4.413334] CPU: 5 UID: 0 PID: 58 Comm: kworker/u32:1 Not tainted 6.12-rc1 #185
[    4.413343] Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
[    4.413362] Call trace:
[    4.413364]  show_stack+0x18/0x24 (C)
[    4.413374]  dump_stack_lvl+0x90/0xd0
[    4.413384]  dump_stack+0x18/0x24
[    4.413392]  register_lock_class+0x498/0x4a8
[    4.413400]  __lock_acquire+0xb4/0x1b90
[    4.413406]  lock_acquire+0x114/0x310
[    4.413413]  _raw_spin_lock_irqsave+0x60/0x88
[    4.413423]  ufshcd_setup_clocks+0x2c0/0x490
[    4.413433]  ufshcd_init+0x198/0x10ec
[    4.413437]  ufshcd_pltfrm_init+0x600/0x7c0
[    4.413444]  ufs_qcom_probe+0x20/0x58
[    4.413449]  platform_probe+0x68/0xd8
[    4.413459]  really_probe+0xbc/0x268
[    4.413466]  __driver_probe_device+0x78/0x12c
[    4.413473]  driver_probe_device+0x40/0x11c
[    4.413481]  __device_attach_driver+0xb8/0xf8
[    4.413489]  bus_for_each_drv+0x84/0xe4
[    4.413495]  __device_attach+0xfc/0x18c
[    4.413502]  device_initial_probe+0x14/0x20
[    4.413510]  bus_probe_device+0xb0/0xb4
[    4.413517]  deferred_probe_work_func+0x8c/0xc8
[    4.413524]  process_scheduled_works+0x250/0x658
[    4.413534]  worker_thread+0x15c/0x2c8
[    4.413542]  kthread+0x134/0x200
[    4.413550]  ret_from_fork+0x10/0x20

To fix this issue, we use the existing `is_initialized` flag in the
`clk_gating` structure to ensure that the spinlock is only used after it
has been properly initialized. We check this flag before using the
spinlock in the `ufshcd_setup_clocks` function.

It was incorrect in the first place to call `setup_clocks()` before
`ufshcd_init_clk_gating()`, and the introduction of the new lock
unmasked this bug.

Fixes: 209f4e43b806 ("scsi: ufs: core: Introduce a new clock_gating lock")
Reported-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Signed-off-by: Avri Altman <avri.altman@....com>
---
 drivers/ufs/core/ufshcd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index f6c38cf10382..a778fc51ca2a 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -9142,7 +9142,7 @@ static int ufshcd_setup_clocks(struct ufs_hba *hba, bool on)
 			if (!IS_ERR_OR_NULL(clki->clk) && clki->enabled)
 				clk_disable_unprepare(clki->clk);
 		}
-	} else if (!ret && on) {
+	} else if (!ret && on && hba->clk_gating.is_initialized) {
 		scoped_guard(spinlock_irqsave, &hba->clk_gating.lock)
 			hba->clk_gating.state = CLKS_ON;
 		trace_ufshcd_clk_gating(dev_name(hba->dev),
-- 
2.25.1