[PATCH] qed: allow sleep in qed_mcp_trace_dump()

* [PATCH] qed: allow sleep in qed_mcp_trace_dump()
@ 2022-12-17 17:56 Caleb Sander
  2022-12-20  9:55 ` Paolo Abeni
       [not found] ` <PH0PR18MB516573B4C93F1A0CC27D5818C4E49@PH0PR18MB5165.namprd18.prod.outlook.com>
  0 siblings, 2 replies; 8+ messages in thread
From: Caleb Sander @ 2022-12-17 17:56 UTC (permalink / raw)
  To: Ariel Elior, Manish Chopra, netdev; +Cc: Joern Engel, Caleb Sander

By default, qed_mcp_cmd_and_union() waits for 10us at a time
in a loop that can run 500K times, so calls to qed_mcp_nvm_rd_cmd()
may block the current thread for over 5s.
We observed thread scheduling delays of over 700ms in production,
with stacktraces pointing to this code as the culprit.

qed_mcp_trace_dump() is called from ethtool, so sleeping is permitted.
It already can sleep in qed_mcp_halt(), which calls qed_mcp_cmd().
Add a "can sleep" parameter to qed_find_nvram_image() and
qed_nvram_read() so they can sleep during qed_mcp_trace_dump().
qed_mcp_trace_get_meta_info() and qed_mcp_trace_read_meta(),
called only by qed_mcp_trace_dump(), allow these functions to sleep.
It's not clear to me that the other caller (qed_grc_dump_mcp_hw_dump())
can sleep, so it keeps b_can_sleep set to false.

Signed-off-by: Caleb Sander <csander@purestorage.com>
---
 drivers/net/ethernet/qlogic/qed/qed_debug.c | 28 +++++++++++++++------
 1 file changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_debug.c b/drivers/net/ethernet/qlogic/qed/qed_debug.c
index 86ecb080b153..cdcead614e9f 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_debug.c
+++ b/drivers/net/ethernet/qlogic/qed/qed_debug.c
@@ -1830,11 +1830,12 @@ static void qed_grc_clear_all_prty(struct qed_hwfn *p_hwfn,
 /* Finds the meta data image in NVRAM */
 static enum dbg_status qed_find_nvram_image(struct qed_hwfn *p_hwfn,
 					    struct qed_ptt *p_ptt,
 					    u32 image_type,
 					    u32 *nvram_offset_bytes,
-					    u32 *nvram_size_bytes)
+					    u32 *nvram_size_bytes,
+					    bool b_can_sleep)
 {
 	u32 ret_mcp_resp, ret_mcp_param, ret_txn_size;
 	struct mcp_file_att file_att;
 	int nvm_result;
 
@@ -1844,11 +1845,12 @@ static enum dbg_status qed_find_nvram_image(struct qed_hwfn *p_hwfn,
 					DRV_MSG_CODE_NVM_GET_FILE_ATT,
 					image_type,
 					&ret_mcp_resp,
 					&ret_mcp_param,
 					&ret_txn_size,
-					(u32 *)&file_att, false);
+					(u32 *)&file_att,
+					b_can_sleep);
 
 	/* Check response */
 	if (nvm_result || (ret_mcp_resp & FW_MSG_CODE_MASK) !=
 	    FW_MSG_CODE_NVM_OK)
 		return DBG_STATUS_NVRAM_GET_IMAGE_FAILED;
@@ -1871,11 +1873,13 @@ static enum dbg_status qed_find_nvram_image(struct qed_hwfn *p_hwfn,
 
 /* Reads data from NVRAM */
 static enum dbg_status qed_nvram_read(struct qed_hwfn *p_hwfn,
 				      struct qed_ptt *p_ptt,
 				      u32 nvram_offset_bytes,
-				      u32 nvram_size_bytes, u32 *ret_buf)
+				      u32 nvram_size_bytes,
+				      u32 *ret_buf,
+				      bool b_can_sleep)
 {
 	u32 ret_mcp_resp, ret_mcp_param, ret_read_size, bytes_to_copy;
 	s32 bytes_left = nvram_size_bytes;
 	u32 read_offset = 0, param = 0;
 
@@ -1897,11 +1901,11 @@ static enum dbg_status qed_nvram_read(struct qed_hwfn *p_hwfn,
 		if (qed_mcp_nvm_rd_cmd(p_hwfn, p_ptt,
 				       DRV_MSG_CODE_NVM_READ_NVRAM, param,
 				       &ret_mcp_resp,
 				       &ret_mcp_param, &ret_read_size,
 				       (u32 *)((u8 *)ret_buf + read_offset),
-				       false))
+				       b_can_sleep))
 			return DBG_STATUS_NVRAM_READ_FAILED;
 
 		/* Check response */
 		if ((ret_mcp_resp & FW_MSG_CODE_MASK) != FW_MSG_CODE_NVM_OK)
 			return DBG_STATUS_NVRAM_READ_FAILED;
@@ -3378,11 +3382,12 @@ static u32 qed_grc_dump_mcp_hw_dump(struct qed_hwfn *p_hwfn,
 	/* Read HW dump image from NVRAM */
 	status = qed_find_nvram_image(p_hwfn,
 				      p_ptt,
 				      NVM_TYPE_HW_DUMP_OUT,
 				      &hw_dump_offset_bytes,
-				      &hw_dump_size_bytes);
+				      &hw_dump_size_bytes,
+				      false);
 	if (status != DBG_STATUS_OK)
 		return 0;
 
 	hw_dump_size_dwords = BYTES_TO_DWORDS(hw_dump_size_bytes);
 
@@ -3395,11 +3400,13 @@ static u32 qed_grc_dump_mcp_hw_dump(struct qed_hwfn *p_hwfn,
 	/* Read MCP HW dump image into dump buffer */
 	if (dump && hw_dump_size_dwords) {
 		status = qed_nvram_read(p_hwfn,
 					p_ptt,
 					hw_dump_offset_bytes,
-					hw_dump_size_bytes, dump_buf + offset);
+					hw_dump_size_bytes,
+					dump_buf + offset,
+					false);
 		if (status != DBG_STATUS_OK) {
 			DP_NOTICE(p_hwfn,
 				  "Failed to read MCP HW Dump image from NVRAM\n");
 			return 0;
 		}
@@ -4121,11 +4128,13 @@ static enum dbg_status qed_mcp_trace_get_meta_info(struct qed_hwfn *p_hwfn,
 	    (*running_bundle_id ==
 	     DIR_ID_1) ? NVM_TYPE_MFW_TRACE1 : NVM_TYPE_MFW_TRACE2;
 	return qed_find_nvram_image(p_hwfn,
 				    p_ptt,
 				    nvram_image_type,
-				    trace_meta_offset, trace_meta_size);
+				    trace_meta_offset,
+				    trace_meta_size,
+				    true);
 }
 
 /* Reads the MCP Trace meta data from NVRAM into the specified buffer */
 static enum dbg_status qed_mcp_trace_read_meta(struct qed_hwfn *p_hwfn,
 					       struct qed_ptt *p_ptt,
@@ -4137,11 +4146,14 @@ static enum dbg_status qed_mcp_trace_read_meta(struct qed_hwfn *p_hwfn,
 	u32 signature;
 
 	/* Read meta data from NVRAM */
 	status = qed_nvram_read(p_hwfn,
 				p_ptt,
-				nvram_offset_in_bytes, size_in_bytes, buf);
+				nvram_offset_in_bytes,
+				size_in_bytes,
+				buf,
+				true);
 	if (status != DBG_STATUS_OK)
 		return status;
 
 	/* Extract and check first signature */
 	signature = qed_read_unaligned_dword(byte_buf);
-- 
2.25.1


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