[PATCH] scsi: ufs: core: Avoid possible memory reclaim deadlock in TX EQTR context

[Can Guo]

TX EQTR may run while devfreq gear scaling has quiesced the UFS tagset. In
that context, functions ufshcd_tx_eqtr(), __ufshcd_tx_eqtr() and
ufs_qcom_get_rx_fom() allocate memory with GFP_KERNEL. If direct reclaim
is triggered, reclaim/writeback can depend on I/O to UFS device. Because
the queue is quiesced, this can cause deadlock.

Use GFP_NOIO for TX EQTR memory allocations:
- params->eqtr_record in ufshcd_tx_eqtr()
- eqtr_data in __ufshcd_tx_eqtr()
- params in ufs_qcom_get_rx_fom()

Fixes: 03e5d38e2f98 ("scsi: ufs: core: Add support for TX Equalization")
Closes: https://sashiko.dev/#/patchset/20260615132834.2985346-1-can.guo@xxxxxxxxxxxxxxxx?part=2
Signed-off-by: Can Guo <can.guo@xxxxxxxxxxxxxxxx>
---
 drivers/ufs/core/ufs-txeq.c | 4 ++--
 drivers/ufs/host/ufs-qcom.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/ufs/core/ufs-txeq.c b/drivers/ufs/core/ufs-txeq.c
index 4b264adfdf49..3a2fb5329d27 100644
--- a/drivers/ufs/core/ufs-txeq.c
+++ b/drivers/ufs/core/ufs-txeq.c
@@ -1059,7 +1059,7 @@ static int __ufshcd_tx_eqtr(struct ufs_hba *hba,
 			    struct ufs_pa_layer_attr *pwr_mode)
 {
 	struct ufshcd_tx_eqtr_data *eqtr_data  __free(kfree) =
-		kzalloc(sizeof(*eqtr_data), GFP_KERNEL);
+		kzalloc(sizeof(*eqtr_data), GFP_NOIO);
 	struct tx_eqtr_iter h_iter = {};
 	struct tx_eqtr_iter d_iter = {};
 	u32 gear = pwr_mode->gear_tx;
@@ -1217,7 +1217,7 @@ static int ufshcd_tx_eqtr(struct ufs_hba *hba,
 	if (!params->eqtr_record) {
 		params->eqtr_record = devm_kzalloc(hba->dev,
 						   sizeof(*params->eqtr_record),
-						   GFP_KERNEL);
+						   GFP_NOIO);
 		if (!params->eqtr_record)
 			return -ENOMEM;
 	}
diff --git a/drivers/ufs/host/ufs-qcom.c b/drivers/ufs/host/ufs-qcom.c
index c084ccc72523..e7f104987c6a 100644
--- a/drivers/ufs/host/ufs-qcom.c
+++ b/drivers/ufs/host/ufs-qcom.c
@@ -2760,7 +2760,7 @@ static int ufs_qcom_get_rx_fom(struct ufs_hba *hba,
 			       struct tx_eqtr_iter *d_iter)
 {
 	struct ufshcd_tx_eq_params *params __free(kfree) =
-		kzalloc(sizeof(*params), GFP_KERNEL);
+		kzalloc(sizeof(*params), GFP_NOIO);
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
 	struct ufs_pa_layer_attr old_pwr_info;
 	u32 fom[PA_MAXDATALANES] = { 0 };
-- 
2.34.1