[PATCH iwl-net v5 7/8] ice: Annotate PTP control PF lock handoff

[Sergey Temerkhanov <sergey.temerkhanov@intel.com>]

ice_ptp_lock() conditionally retains ctrl_pf_lock for read when it
successfully acquires the hardware semaphore. The matching unlock occurs
in ice_ptp_unlock(). Describe this cross-function handoff with context
analysis annotations so static analysis can verify callers.

Signed-off-by: Sergey Temerkhanov <sergey.temerkhanov@intel.com>
Reviewed-by: Przemyslaw Korba <przemyslaw.korba@intel.com>
---
 drivers/net/ethernet/intel/ice/ice.h        | 12 ++++++++++
 drivers/net/ethernet/intel/ice/ice_ptp_hw.c | 26 +++++++++++++--------
 drivers/net/ethernet/intel/ice/ice_ptp_hw.h |  6 +++--
 3 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice.h b/drivers/net/ethernet/intel/ice/ice.h
index c454f19a2cb2..8b7891ac25b0 100644
--- a/drivers/net/ethernet/intel/ice/ice.h
+++ b/drivers/net/ethernet/intel/ice/ice.h
@@ -1179,4 +1179,16 @@ static inline struct ice_pf *ice_get_ctrl_pf(struct ice_pf *pf)
 		rcu_dereference_check(pf->adapter->ctrl_pf,
 				      lockdep_is_held(&pf->adapter->ctrl_pf_lock));
 }
+
+/* container_of() expands to a statement expression, which clang cannot parse
+ * inside a context analysis attribute argument, so open-code the cast here.
+ */
+#define ice_hw_ctrl_pf_lock(_hw)					\
+	(&((struct ice_pf *)((void *)(_hw) -				\
+			     offsetof(struct ice_pf, hw)))->adapter->ctrl_pf_lock)
+
+bool ice_ptp_lock(struct ice_hw *hw)
+	__cond_acquires_shared(true, ice_hw_ctrl_pf_lock(hw));
+void ice_ptp_unlock(struct ice_hw *hw)
+	__releases_shared(ice_hw_ctrl_pf_lock(hw));
 #endif /* _ICE_H_ */
diff --git a/drivers/net/ethernet/intel/ice/ice_ptp_hw.c b/drivers/net/ethernet/intel/ice/ice_ptp_hw.c
index a85aa8f99057..eb7fdd000cf2 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp_hw.c
+++ b/drivers/net/ethernet/intel/ice/ice_ptp_hw.c
@@ -5361,15 +5361,16 @@ static void ice_ptp_init_phy_e830(struct ice_ptp_hw *ptp)
 bool ice_ptp_lock(struct ice_hw *hw)
 {
 	struct ice_pf *pf = container_of(hw, struct ice_pf, hw);
+	struct ice_hw *pri_hw = hw;
 	u32 hw_lock;
 	int i;
 
-	down_read(&pf->adapter->ctrl_pf_lock);
+	down_read(ice_hw_ctrl_pf_lock(hw));
 
 	if (!ice_is_primary(hw)) {
-		hw = ice_get_primary_hw(pf);
-		if (!hw) {
-			up_read(&pf->adapter->ctrl_pf_lock);
+		pri_hw = ice_get_primary_hw(pf);
+		if (!pri_hw) {
+			up_read(ice_hw_ctrl_pf_lock(hw));
 			return false;
 		}
 	}
@@ -5377,7 +5378,8 @@ bool ice_ptp_lock(struct ice_hw *hw)
 #define MAX_TRIES 15
 
 	for (i = 0; i < MAX_TRIES; i++) {
-		hw_lock = rd32(hw, PFTSYN_SEM + (PFTSYN_SEM_BYTES * hw->pf_id));
+		hw_lock = rd32(pri_hw,
+			       PFTSYN_SEM + (PFTSYN_SEM_BYTES * pri_hw->pf_id));
 		hw_lock = hw_lock & PFTSYN_SEM_BUSY_M;
 		if (hw_lock) {
 			/* Somebody is holding the lock */
@@ -5389,7 +5391,7 @@ bool ice_ptp_lock(struct ice_hw *hw)
 	}
 
 	if (hw_lock)
-		up_read(&pf->adapter->ctrl_pf_lock);
+		up_read(ice_hw_ctrl_pf_lock(hw));
 
 	return !hw_lock;
 }
@@ -5404,14 +5406,18 @@ bool ice_ptp_lock(struct ice_hw *hw)
 void ice_ptp_unlock(struct ice_hw *hw)
 {
 	struct ice_pf *pf = container_of(hw, struct ice_pf, hw);
+	struct ice_hw *pri_hw = hw;
 
-	lockdep_assert_held(&pf->adapter->ctrl_pf_lock);
+	lockdep_assert_held(ice_hw_ctrl_pf_lock(hw));
 
+	/* ctrl_pf cannot be cleared while ctrl_pf_lock is held for read, so a
+	 * successful ice_ptp_lock() guarantees a primary hw is still there.
+	 */
 	if (!ice_is_primary(hw))
-		hw = ice_get_primary_hw(pf);
+		pri_hw = ice_get_primary_hw(pf);
 
-	wr32(hw, PFTSYN_SEM + (PFTSYN_SEM_BYTES * hw->pf_id), 0);
-	up_read(&pf->adapter->ctrl_pf_lock);
+	wr32(pri_hw, PFTSYN_SEM + (PFTSYN_SEM_BYTES * pri_hw->pf_id), 0);
+	up_read(ice_hw_ctrl_pf_lock(hw));
 }
 
 /**
diff --git a/drivers/net/ethernet/intel/ice/ice_ptp_hw.h b/drivers/net/ethernet/intel/ice/ice_ptp_hw.h
index 16b1988e993d..ce8eb0672e71 100644
--- a/drivers/net/ethernet/intel/ice/ice_ptp_hw.h
+++ b/drivers/net/ethernet/intel/ice/ice_ptp_hw.h
@@ -293,8 +293,10 @@ extern const struct ice_vernier_info_e82x e822_vernier[NUM_ICE_PTP_LNK_SPD];
 
 /* Device agnostic functions */
 u8 ice_get_ptp_src_clock_index(struct ice_hw *hw);
-bool ice_ptp_lock(struct ice_hw *hw);
-void ice_ptp_unlock(struct ice_hw *hw);
+/* ice_ptp_lock()/ice_ptp_unlock() are declared in ice.h, where struct ice_pf
+ * and struct ice_adapter are complete and ice_hw_ctrl_pf_lock() can be used
+ * in their context analysis annotations.
+ */
 void ice_ptp_src_cmd(struct ice_hw *hw, enum ice_ptp_tmr_cmd cmd);
 int ice_ptp_init_time(struct ice_hw *hw, u64 time);
 int ice_ptp_write_incval(struct ice_hw *hw, u64 incval);
-- 
2.53.0