There is a lock inversion and rwsem read-lock recursion in the devfreq
target callback which can lead to deadlocks.
Specifically, ufshcd_devfreq_scale() already holds a clk_scaling_lock
read lock when toggling the write booster, which involves taking the
dev_cmd mutex before taking another clk_scaling_lock read lock.
This can lead to a deadlock if another thread:
1) tries to acquire the dev_cmd and clk_scaling locks in the correct
order, or
2) takes a clk_scaling write lock before the attempt to take the
clk_scaling read lock a second time.
Fix this by dropping the clk_scaling_lock before toggling the write booster
as was done before commit 0e9d4ca43b ("scsi: ufs: Protect some contexts
from unexpected clock scaling").
While the devfreq callbacks are already serialised, add a second
serialising mutex to handle the unlikely case where a callback triggered
through the devfreq sysfs interface is racing with a request to disable
clock scaling through the UFS controller 'clkscale_enable' sysfs
attribute. This could otherwise lead to the write booster being left
disabled after having disabled clock scaling.
Also take the new mutex in ufshcd_clk_scaling_allow() to make sure that any
pending write booster update has completed on return.
Note that this currently only affects Qualcomm platforms since commit
87bd05016a ("scsi: ufs: core: Allow host driver to disable wb toggling
during clock scaling").
The lock inversion (i.e. 1 above) was reported by lockdep as:
======================================================
WARNING: possible circular locking dependency detected
6.1.0-next-20221216 #211 Not tainted
------------------------------------------------------
kworker/u16:2/71 is trying to acquire lock:
ffff076280ba98a0 (&hba->dev_cmd.lock){+.+.}-{3:3}, at: ufshcd_query_flag+0x50/0x1c0
but task is already holding lock:
ffff076280ba9cf0 (&hba->clk_scaling_lock){++++}-{3:3}, at: ufshcd_devfreq_scale+0x2b8/0x380
which lock already depends on the new lock.
[ +0.011606]
the existing dependency chain (in reverse order) is:
-> #1 (&hba->clk_scaling_lock){++++}-{3:3}:
lock_acquire+0x68/0x90
down_read+0x58/0x80
ufshcd_exec_dev_cmd+0x70/0x2c0
ufshcd_verify_dev_init+0x68/0x170
ufshcd_probe_hba+0x398/0x1180
ufshcd_async_scan+0x30/0x320
async_run_entry_fn+0x34/0x150
process_one_work+0x288/0x6c0
worker_thread+0x74/0x450
kthread+0x118/0x120
ret_from_fork+0x10/0x20
-> #0 (&hba->dev_cmd.lock){+.+.}-{3:3}:
__lock_acquire+0x12a0/0x2240
lock_acquire.part.0+0xcc/0x220
lock_acquire+0x68/0x90
__mutex_lock+0x98/0x430
mutex_lock_nested+0x2c/0x40
ufshcd_query_flag+0x50/0x1c0
ufshcd_query_flag_retry+0x64/0x100
ufshcd_wb_toggle+0x5c/0x120
ufshcd_devfreq_scale+0x2c4/0x380
ufshcd_devfreq_target+0xf4/0x230
devfreq_set_target+0x84/0x2f0
devfreq_update_target+0xc4/0xf0
devfreq_monitor+0x38/0x1f0
process_one_work+0x288/0x6c0
worker_thread+0x74/0x450
kthread+0x118/0x120
ret_from_fork+0x10/0x20
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&hba->clk_scaling_lock);
lock(&hba->dev_cmd.lock);
lock(&hba->clk_scaling_lock);
lock(&hba->dev_cmd.lock);
*** DEADLOCK ***
Fixes: 0e9d4ca43b ("scsi: ufs: Protect some contexts from unexpected clock scaling")
Cc: stable@vger.kernel.org # 5.12
Cc: Can Guo <quic_cang@quicinc.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20230116161201.16923-1-johan+linaro@kernel.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Commit 68078d5cc1 ("[SCSI] ufs: Set fDeviceInit flag to initiate device
initialization") added check_upiu_size(), but no caller.
Cc: Dolev Raviv <draviv@codeaurora.org>
Link: https://lore.kernel.org/r/20221103055349epcms2p338f2550c2dd78d00231a83b24719a3d4@epcms2p3
Signed-off-by: Keoseong Park <keosung.park@samsung.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add a new boolean variable that tracks whether the system is suspending,
suspended or resuming. This information will be used in a later commit to
fix a deadlock between the SCSI error handler and the suspend code.
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20221018202958.1902564-9-bvanassche@acm.org
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Remove Query-Request API function declarations from include/ufs/ufshcd.h
and move them to the ufs core private header.
Link: https://lore.kernel.org/r/1663761485-2532-1-git-send-email-Arthur.Simchaev@wdc.com
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Arthur Simchaev <Arthur.Simchaev@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
There is the following quirk to bypass "WB Flush" in Write Booster.
- UFSHCI_QUIRK_SKIP_MANUAL_WB_FLUSH_CTRL
If this quirk is not set, there is no knob that can control "WB Flush".
There are three flags that control Write Booster Feature:
1. WB ON/OFF
2. WB Hibern Flush ON/OFF (implicitly)
3. WB Flush ON/OFF (explicit)
The sysfs attribute that controls the WB was implemented. (1)
In the case of "Hibern Flush", it is always good to turn on. Control may
not be required. (2)
Finally, "Flush" may be necessary because the Auto-Hibern8 is not supported
in a specific environment. So the sysfs attribute that controls this is
necessary. (3)
Link: https://lore.kernel.org/r/20220804075354epcms2p8c21c894b4e28840c5fc651875b7f435f@epcms2p8
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Jinyoung Choi <j-young.choi@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Mediatek UFS does not want to toggle write booster during clock scaling.
Permit host driver to disable wb toggling during clock scaling.
Introduce a flag UFSHCD_CAP_WB_WITH_CLK_SCALING to decouple WB and clock
scaling. UFSHCD_CAP_WB_WITH_CLK_SCALING is only valid when
UFSHCD_CAP_CLK_SCALING is set. Just like UFSHCD_CAP_HIBERN8_WITH_CLK_GATING
is valid only when UFSHCD_CAP_CLK_GATING set.
Set UFSHCD_CAP_WB_WITH_CLK_SCALING for qcom to compatible legacy design at
the same time.
Link: https://lore.kernel.org/r/20220804025422.18803-1-peter.wang@mediatek.com
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
CLOCK_MONOTONIC is not advanced when the system is in suspend. This becomes
problematic when debugging issues related to suspend-resume: the timestamps
printed by ufshcd_print_trs can not be correlated with dmesg entries, which
are timestamped with local_clock().
Change the used clock to local_clock() for the informational timestamp
variables and adds mirroring *_local_clock instances for variables used in
subsequent derevations (to not change the semantics of those derevations).
Link: https://lore.kernel.org/r/20220804065019.v5.1.I699244ea7efbd326a34a6dfd9b5a31e78400cf68@changeid
Acked-by: Stanley Chu <stanley.chu@mediatek.com>
Acked-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Daniil Lunev <dlunev@chromium.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
For code safety, constify arrays and pointers to data which is not
modified.
Link: https://lore.kernel.org/r/20220623102432.108059-4-krzysztof.kozlowski@linaro.org
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Export below regulator functions to allow vendors to
customize regulator configuration in their own platforms.
int ufshcd_populate_vreg(struct device *dev, const char *name,
struct ufs_vreg **out_vreg);
int ufshcd_get_vreg(struct device *dev, struct ufs_vreg *vreg);
Link: https://lore.kernel.org/r/20220616053725.5681-10-stanley.chu@mediatek.com
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Export ufshcd_uic_change_pwr_mode() to allow vendors to use it for
SoC-specific power mode change design limitations.
Link: https://lore.kernel.org/r/20220616053725.5681-2-stanley.chu@mediatek.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Add UFSHCD_QUIRK_HIBERN_FASTAUTO quirk for host controllers which supports
auto-hibernate the capability but only FASTAUTO mode.
Link: https://lore.kernel.org/r/20220603110524.1997825-4-yoshihiro.shimoda.uh@renesas.com
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Split the drivers/scsi/ufs directory into 'core' and 'host' directories
under the drivers/ufs/ directory. Move shared header files into the
include/ufs/ directory. This separation makes it clear which header files
UFS drivers are allowed to include (include/ufs/*.h) and which header files
UFS drivers are not allowed to include (drivers/ufs/core/*.h).
Update the MAINTAINERS file. Add myself as a UFS reviewer.
Link: https://lore.kernel.org/r/20220511212552.655341-1-bvanassche@acm.org
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Avri Altman <avri.altman@wdc.com>
Cc: Bean Huo <beanhuo@micron.com>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Keoseong Park <keosung.park@samsung.com>
Tested-by: Bean Huo <beanhuo@micron.com>
Tested-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Acked-by: Avri Altman <avri.altman@wdc.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
