[PATCH net-next] bnxt_en: Fix 64-bit doorbell operation on 32-bit kernels

[PATCH net-next] bnxt_en: Fix 64-bit doorbell operation on 32-bit kernels

[Michael Chan]

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The driver requires 64-bit doorbell writes to be atomic on 32-bit
architectures.  So we redefined writeq as a new macro with spinlock
protection on 32-bit architectures.  This created a new warning when
we added a new file in a recent patchset.  writeq is defined on many
32-bit architectures to do the memory write non-atomically and it
generated a new macro redefined warning.  This warning was fixed
incorrectly in the recent patch.

Fix this properly by adding a new bnxt_writeq() function that will
do the non-atomic write under spinlock on 32-bit systems.  All callers
in the driver will now call bnxt_writeq() instead.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: f9ff578251dc ("bnxt_en: introduce new firmware message API based on DMA pools")
Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c | 14 +++++-----
 drivers/net/ethernet/broadcom/bnxt/bnxt.h | 33 ++++++++++++++---------
 2 files changed, 29 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 627f85ee3922..5b145077d21a 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -305,13 +305,15 @@ static bool bnxt_vf_pciid(enum board_idx idx)
 	writel(DB_CP_FLAGS | RING_CMP(idx), (db)->doorbell)
 
 #define BNXT_DB_NQ_P5(db, idx)						\
-	writeq((db)->db_key64 | DBR_TYPE_NQ | RING_CMP(idx), (db)->doorbell)
+	bnxt_writeq((db)->db_key64 | DBR_TYPE_NQ | RING_CMP(idx),	\
+		    (db)->doorbell)
 
 #define BNXT_DB_CQ_ARM(db, idx)						\
 	writel(DB_CP_REARM_FLAGS | RING_CMP(idx), (db)->doorbell)
 
 #define BNXT_DB_NQ_ARM_P5(db, idx)					\
-	writeq((db)->db_key64 | DBR_TYPE_NQ_ARM | RING_CMP(idx), (db)->doorbell)
+	bnxt_writeq((db)->db_key64 | DBR_TYPE_NQ_ARM | RING_CMP(idx),	\
+		    (db)->doorbell)
 
 static void bnxt_db_nq(struct bnxt *bp, struct bnxt_db_info *db, u32 idx)
 {
@@ -332,8 +334,8 @@ static void bnxt_db_nq_arm(struct bnxt *bp, struct bnxt_db_info *db, u32 idx)
 static void bnxt_db_cq(struct bnxt *bp, struct bnxt_db_info *db, u32 idx)
 {
 	if (bp->flags & BNXT_FLAG_CHIP_P5)
-		writeq(db->db_key64 | DBR_TYPE_CQ_ARMALL | RING_CMP(idx),
-		       db->doorbell);
+		bnxt_writeq(db->db_key64 | DBR_TYPE_CQ_ARMALL | RING_CMP(idx),
+			    db->doorbell);
 	else
 		BNXT_DB_CQ(db, idx);
 }
@@ -2638,8 +2640,8 @@ static void __bnxt_poll_cqs_done(struct bnxt *bp, struct bnxt_napi *bnapi,
 
 		if (cpr2 && cpr2->had_work_done) {
 			db = &cpr2->cp_db;
-			writeq(db->db_key64 | dbr_type |
-			       RING_CMP(cpr2->cp_raw_cons), db->doorbell);
+			bnxt_writeq(db->db_key64 | dbr_type |
+				    RING_CMP(cpr2->cp_raw_cons), db->doorbell);
 			cpr2->had_work_done = 0;
 		}
 	}
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index a8212dcdad5f..e69d4a1d0c63 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -1981,7 +1981,7 @@ struct bnxt {
 	struct mutex		sriov_lock;
 #endif
 
-#ifndef writeq
+#if BITS_PER_LONG == 32
 	/* ensure atomic 64-bit doorbell writes on 32-bit systems. */
 	spinlock_t		db_lock;
 #endif
@@ -2110,24 +2110,33 @@ static inline u32 bnxt_tx_avail(struct bnxt *bp, struct bnxt_tx_ring_info *txr)
 		((txr->tx_prod - txr->tx_cons) & bp->tx_ring_mask);
 }
 
-#ifndef writeq
-#define writeq(val64, db)			\
-do {						\
-	spin_lock(&bp->db_lock);		\
-	writel((val64) & 0xffffffff, db);	\
-	writel((val64) >> 32, (db) + 4);	\
-	spin_unlock(&bp->db_lock);		\
-} while (0)
+static inline void bnxt_writeq(u64 val, volatile void __iomem *addr)
+{
+#if BITS_PER_LONG == 32
+	spin_lock(&bp->db_lock);
+	writel(val & 0xffffffff, addr);
+	writel(val >> 32, addr + 4);
+	spin_unlock(&bp->db_lock);
+#else
+	writeq(val, addr);
+#endif
+}
 
-#define writeq_relaxed writeq
+static inline void bnxt_writeq_relaxed(u64 val, volatile void __iomem *addr)
+{
+#if BITS_PER_LONG == 32
+	bnxt_writeq(val, addr);
+#else
+	writeq_relaxed(val, addr);
 #endif
+}
 
 /* For TX and RX ring doorbells with no ordering guarantee*/
 static inline void bnxt_db_write_relaxed(struct bnxt *bp,
 					 struct bnxt_db_info *db, u32 idx)
 {
 	if (bp->flags & BNXT_FLAG_CHIP_P5) {
-		writeq_relaxed(db->db_key64 | idx, db->doorbell);
+		bnxt_writeq_relaxed(db->db_key64 | idx, db->doorbell);
 	} else {
 		u32 db_val = db->db_key32 | idx;
 
@@ -2142,7 +2151,7 @@ static inline void bnxt_db_write(struct bnxt *bp, struct bnxt_db_info *db,
 				 u32 idx)
 {
 	if (bp->flags & BNXT_FLAG_CHIP_P5) {
-		writeq(db->db_key64 | idx, db->doorbell);
+		bnxt_writeq(db->db_key64 | idx, db->doorbell);
 	} else {
 		u32 db_val = db->db_key32 | idx;
 
-- 
2.18.1


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Re: [PATCH net-next] bnxt_en: Fix 64-bit doorbell operation on 32-bit kernels

[Jakub Kicinski]

On Tue, 31 Aug 2021 18:28:45 -0400 Michael Chan wrote:
> The driver requires 64-bit doorbell writes to be atomic on 32-bit
> architectures.  So we redefined writeq as a new macro with spinlock
> protection on 32-bit architectures.  This created a new warning when
> we added a new file in a recent patchset.  writeq is defined on many
> 32-bit architectures to do the memory write non-atomically and it
> generated a new macro redefined warning.  This warning was fixed
> incorrectly in the recent patch.
> 
> Fix this properly by adding a new bnxt_writeq() function that will
> do the non-atomic write under spinlock on 32-bit systems.  All callers
> in the driver will now call bnxt_writeq() instead.
> 
> Reported-by: kernel test robot <lkp@intel.com>
> Fixes: f9ff578251dc ("bnxt_en: introduce new firmware message API based on DMA pools")
> Reviewed-by: Edwin Peer <edwin.peer@broadcom.com>
> Signed-off-by: Michael Chan <michael.chan@broadcom.com>

Lots of these:

drivers/net/ethernet/broadcom/bnxt/bnxt.h: In function ‘bnxt_writeq’:
drivers/net/ethernet/broadcom/bnxt/bnxt.h:2116:13: error: ‘bp’ undeclared (first use in this function); did you mean ‘up’?
 2116 |  spin_lock(&bp->db_lock);
      |             ^~
      |             up