[PATCH] Add dynamic trace point for timeouts waiting for credits

[PATCH] Add dynamic trace point for timeouts waiting for credits

[Steve French]

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Thanks,

Steve

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From 0551fe7c680f5a3bb33a5c28d8f713dd562462b9 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Sat, 9 Mar 2019 20:29:55 -0600
Subject: [PATCH] smb3: add dynamic tracepoint for timeout waiting for credits

To help debug credit starvation problems where we timeout
waiting for server to grant the client credits.

Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/trace.h     | 1 +
 fs/cifs/transport.c | 5 +++++
 2 files changed, 6 insertions(+)

diff --git a/fs/cifs/trace.h b/fs/cifs/trace.h
index d8b049afa606..c78e96c4cc53 100644
--- a/fs/cifs/trace.h
+++ b/fs/cifs/trace.h
@@ -713,6 +713,7 @@ DEFINE_EVENT(smb3_credit_class, smb3_##name,  \
 	TP_ARGS(currmid, hostname, credits))
 
 DEFINE_SMB3_CREDIT_EVENT(reconnect_with_invalid_credits);
+DEFINE_SMB3_CREDIT_EVENT(credit_timeout);
 
 #endif /* _CIFS_TRACE_H */
 
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index b3d04018195c..8731cfa66026 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -527,6 +527,8 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 				has_credits(server, credits, num_credits), t);
 			cifs_num_waiters_dec(server);
 			if (!rc) {
+				trace_smb3_credit_timeout(server->CurrentMid,
+					server->hostname, num_credits);
 				cifs_dbg(VFS, "wait timed out after %d ms\n",
 					 timeout);
 				return -ENOTSUPP;
@@ -565,6 +567,9 @@ wait_for_free_credits(struct TCP_Server_Info *server, const int num_credits,
 					t);
 				cifs_num_waiters_dec(server);
 				if (!rc) {
+					trace_smb3_credit_timeout(
+						server->CurrentMid,
+						server->hostname, num_credits);
 					cifs_dbg(VFS, "wait timed out after %d ms\n",
 						 timeout);
 					return -ENOTSUPP;
-- 
2.17.1

Re: [PATCH] Add dynamic trace point for timeouts waiting for credits

[Pavel Shilovsky]

Looks good.

Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
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Best regards,
Pavel Shilovsky