linux-kernel - [PATCH ath-next v4 2/9] wifi: ath12k: add reference counting for core attachment to hardware group

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Message-Id: <20250408-fix_reboot_issues_with_hw_grouping-v4-2-95e7bf048595@oss.qualcomm.com>
Date: Tue, 08 Apr 2025 11:36:30 +0530
From: Aditya Kumar Singh <aditya.kumar.singh@....qualcomm.com>
To: Johannes Berg <johannes@...solutions.net>,
        Jeff Johnson <jjohnson@...nel.org>,
        Karthikeyan Periyasamy <quic_periyasa@...cinc.com>,
        Kalle Valo <kvalo@...nel.org>, Harshitha Prem <quic_hprem@...cinc.com>
Cc: Jeff Johnson <jeff.johnson@....qualcomm.com>,
        linux-wireless@...r.kernel.org, ath12k@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Aditya Kumar Singh <aditya.kumar.singh@....qualcomm.com>
Subject: [PATCH ath-next v4 2/9] wifi: ath12k: add reference counting for
 core attachment to hardware group

Currently, driver does not manage reference counting for attaching and
detaching cores to/from hardware groups. This can lead to issues when
multiple cores are involved. Or with same core, attach/detach is called
multiple times back to back.

Fix this issue by using reference counting.

With that, it is now ensured that the core is properly attached or detached
from the hardware group and even back to back calls will not alter the
count.

Additionally, add some debug logs during the attachment and detachment
events for better debugging and tracking.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.3.1-00173-QCAHKSWPL_SILICONZ-1
Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-QCAHKSWPL_SILICONZ-1
Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3

Signed-off-by: Aditya Kumar Singh <aditya.kumar.singh@....qualcomm.com>
---
 drivers/net/wireless/ath/ath12k/core.c | 47 +++++++++++++++++++++++++++++++---
 drivers/net/wireless/ath/ath12k/core.h | 15 +----------
 2 files changed, 44 insertions(+), 18 deletions(-)

diff --git a/drivers/net/wireless/ath/ath12k/core.c b/drivers/net/wireless/ath/ath12k/core.c
index 0e71935b272033c5322e76a01e931087ced875ca..8a571a615313d2f1190fe9afae02dfd385ede7a3 100644
--- a/drivers/net/wireless/ath/ath12k/core.c
+++ b/drivers/net/wireless/ath/ath12k/core.c
@@ -640,9 +640,49 @@ struct reserved_mem *ath12k_core_get_reserved_mem(struct ath12k_base *ab,
 	return rmem;
 }
 
+static inline
+void ath12k_core_to_group_ref_get(struct ath12k_base *ab)
+{
+	struct ath12k_hw_group *ag = ab->ag;
+
+	lockdep_assert_held(&ag->mutex);
+
+	if (ab->hw_group_ref) {
+		ath12k_dbg(ab, ATH12K_DBG_BOOT, "core already attached to group %d\n",
+			   ag->id);
+		return;
+	}
+
+	ab->hw_group_ref = true;
+	ag->num_started++;
+
+	ath12k_dbg(ab, ATH12K_DBG_BOOT, "core attached to group %d, num_started %d\n",
+		   ag->id, ag->num_started);
+}
+
+static inline
+void ath12k_core_to_group_ref_put(struct ath12k_base *ab)
+{
+	struct ath12k_hw_group *ag = ab->ag;
+
+	lockdep_assert_held(&ag->mutex);
+
+	if (!ab->hw_group_ref) {
+		ath12k_dbg(ab, ATH12K_DBG_BOOT, "core already de-attached from group %d\n",
+			   ag->id);
+		return;
+	}
+
+	ab->hw_group_ref = false;
+	ag->num_started--;
+
+	ath12k_dbg(ab, ATH12K_DBG_BOOT, "core de-attached from group %d, num_started %d\n",
+		   ag->id, ag->num_started);
+}
+
 static void ath12k_core_stop(struct ath12k_base *ab)
 {
-	ath12k_core_stopped(ab);
+	ath12k_core_to_group_ref_put(ab);
 
 	if (!test_bit(ATH12K_FLAG_CRASH_FLUSH, &ab->dev_flags))
 		ath12k_qmi_firmware_stop(ab);
@@ -879,9 +919,8 @@ static int ath12k_core_start(struct ath12k_base *ab)
 
 	ath12k_acpi_set_dsm_func(ab);
 
-	if (!test_bit(ATH12K_FLAG_RECOVERY, &ab->dev_flags))
-		/* Indicate the core start in the appropriate group */
-		ath12k_core_started(ab);
+	/* Indicate the core start in the appropriate group */
+	ath12k_core_to_group_ref_get(ab);
 
 	return 0;
 
diff --git a/drivers/net/wireless/ath/ath12k/core.h b/drivers/net/wireless/ath/ath12k/core.h
index e8d2a0c859f6260d48c4c636793cf3a24c1c61b6..75fb4a99af9442e3c3f042602cc5b26842aa5231 100644
--- a/drivers/net/wireless/ath/ath12k/core.h
+++ b/drivers/net/wireless/ath/ath12k/core.h
@@ -1121,6 +1121,7 @@ struct ath12k_base {
 	struct ath12k_wsi_info wsi_info;
 	enum ath12k_firmware_mode fw_mode;
 	struct ath12k_ftm_event_obj ftm_event_obj;
+	bool hw_group_ref;
 
 	/* must be last */
 	u8 drv_priv[] __aligned(sizeof(void *));
@@ -1375,20 +1376,6 @@ static inline struct ath12k_hw_group *ath12k_ab_to_ag(struct ath12k_base *ab)
 	return ab->ag;
 }
 
-static inline void ath12k_core_started(struct ath12k_base *ab)
-{
-	lockdep_assert_held(&ab->ag->mutex);
-
-	ab->ag->num_started++;
-}
-
-static inline void ath12k_core_stopped(struct ath12k_base *ab)
-{
-	lockdep_assert_held(&ab->ag->mutex);
-
-	ab->ag->num_started--;
-}
-
 static inline struct ath12k_base *ath12k_ag_to_ab(struct ath12k_hw_group *ag,
 						  u8 device_id)
 {

-- 
2.34.1