smb3: add tracepoint to catch cases where credit refund of failed op overlaps reconnect
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Message ID CAH2r5ms6pDBGyT2UrhPd_A80pvdkbDBTCA5WbjZUzisu6Z=arQ@mail.gmail.com
State New
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Series
  • smb3: add tracepoint to catch cases where credit refund of failed op overlaps reconnect
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Commit Message

Steve French Sept. 1, 2018, 6:15 a.m. UTC
Add tracepoint to catch potential cases where a pending operation overlapping a
reconnect could fail and incorrectly refund its credits causing the client
to think it has more credits available than the server thinks it does.

Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/smb2ops.c |  6 ++++++
 fs/cifs/trace.h   | 30 ++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

Patch
diff mbox series

From 971b5a5926d52186b7428b6f4ae2a0f6794552e2 Mon Sep 17 00:00:00 2001
From: Steve French <stfrench@microsoft.com>
Date: Sat, 1 Sep 2018 01:10:17 -0500
Subject: [PATCH] smb3: add tracepoint to catch cases where credit refund of
 failed op overlaps reconnect

Add tracepoint to catch potential cases where a pending operation overlapping a
reconnect could fail and incorrectly refund its credits causing the client
to think it has more credits available than the server thinks it does.

Signed-off-by: Steve French <stfrench@microsoft.com>
---
 fs/cifs/smb2ops.c |  6 ++++++
 fs/cifs/trace.h   | 30 ++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index 23118b7a2bbc..61ecf7eb8842 100644
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -74,6 +74,12 @@  smb2_add_credits(struct TCP_Server_Info *server, const unsigned int add,
 	int *val, rc = 0;
 	spin_lock(&server->req_lock);
 	val = server->ops->get_credits_field(server, optype);
+
+	/* eg found case where write overlapping reconnect messed up credits */
+	if (((optype & CIFS_OP_MASK) == CIFS_NEG_OP) && (*val != 0))
+		trace_smb3_reconnect_with_invalid_credits(server->CurrentMid,
+			server->hostname, *val);
+
 	*val += add;
 	if (*val > 65000) {
 		*val = 65000; /* Don't get near 64K credits, avoid srv bugs */
diff --git a/fs/cifs/trace.h b/fs/cifs/trace.h
index d4aed5217a56..43e5bd417b81 100644
--- a/fs/cifs/trace.h
+++ b/fs/cifs/trace.h
@@ -486,6 +486,36 @@  DEFINE_EVENT(smb3_reconnect_class, smb3_##name,  \
 DEFINE_SMB3_RECONNECT_EVENT(reconnect);
 DEFINE_SMB3_RECONNECT_EVENT(partial_send_reconnect);
 
+DECLARE_EVENT_CLASS(smb3_credit_class,
+	TP_PROTO(__u64	currmid,
+		char *hostname,
+		int credits),
+	TP_ARGS(currmid, hostname, credits),
+	TP_STRUCT__entry(
+		__field(__u64, currmid)
+		__field(char *, hostname)
+		__field(int, credits)
+	),
+	TP_fast_assign(
+		__entry->currmid = currmid;
+		__entry->hostname = hostname;
+		__entry->credits = credits;
+	),
+	TP_printk("server=%s current_mid=0x%llx credits=%d",
+		__entry->hostname,
+		__entry->currmid,
+		__entry->credits)
+)
+
+#define DEFINE_SMB3_CREDIT_EVENT(name)        \
+DEFINE_EVENT(smb3_credit_class, smb3_##name,  \
+	TP_PROTO(__u64	currmid,		\
+		char *hostname,			\
+		int  credits),			\
+	TP_ARGS(currmid, hostname, credits))
+
+DEFINE_SMB3_CREDIT_EVENT(reconnect_with_invalid_credits);
+
 #endif /* _CIFS_TRACE_H */
 
 #undef TRACE_INCLUDE_PATH
-- 
2.17.1