Commit 96c4af41 authored by Shyam Prasad N's avatar Shyam Prasad N Committed by Steve French
Browse files

cifs: Fix locking usage for tcon fields 



We used to use the cifs_tcp_ses_lock to protect a lot of objects
that are not just the server, ses or tcon lists. We later introduced
srv_lock, ses_lock and tc_lock to protect fields within the
corresponding structs. This was done to provide a more granular
protection and avoid unnecessary serialization.

There were still a couple of uses of cifs_tcp_ses_lock to provide
tcon fields. In this patch, I've replaced them with tc_lock.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 037ddbcc

fs/smb/client/cached_dir.c

+2 −2
Original line number Diff line number Diff line
@@ -792,11 +792,11 @@ static void cfids_laundromat_worker(struct work_struct *work) 
		cfid->dentry = NULL;



		if (cfid->is_open) {

			spin_lock(&cifs_tcp_ses_lock);

			spin_lock(&cfid->tcon->tc_lock);

			++cfid->tcon->tc_count;

			trace_smb3_tcon_ref(cfid->tcon->debug_id, cfid->tcon->tc_count,

					    netfs_trace_tcon_ref_get_cached_laundromat);

			spin_unlock(&cifs_tcp_ses_lock);

			spin_unlock(&cfid->tcon->tc_lock);

			queue_work(serverclose_wq, &cfid->close_work);

		} else

			/*

fs/smb/client/smb2misc.c

+3 −3
Original line number Diff line number Diff line
@@ -820,14 +820,14 @@ smb2_handle_cancelled_close(struct cifs_tcon *tcon, __u64 persistent_fid, 
	int rc;



	cifs_dbg(FYI, "%s: tc_count=%d\n", __func__, tcon->tc_count);

	spin_lock(&cifs_tcp_ses_lock);

	spin_lock(&tcon->tc_lock);

	if (tcon->tc_count <= 0) {

		struct TCP_Server_Info *server = NULL;



		trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,

				    netfs_trace_tcon_ref_see_cancelled_close);

		WARN_ONCE(tcon->tc_count < 0, "tcon refcount is negative");

		spin_unlock(&cifs_tcp_ses_lock);

		spin_unlock(&tcon->tc_lock);



		if (tcon->ses) {

			server = tcon->ses->server;
@@ -841,7 +841,7 @@ smb2_handle_cancelled_close(struct cifs_tcon *tcon, __u64 persistent_fid, 
	tcon->tc_count++;

	trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,

			    netfs_trace_tcon_ref_get_cancelled_close);

	spin_unlock(&cifs_tcp_ses_lock);

	spin_unlock(&tcon->tc_lock);



	rc = __smb2_handle_cancelled_cmd(tcon, SMB2_CLOSE_HE, 0,

					 persistent_fid, volatile_fid);

fs/smb/client/smb2ops.c

+3 −5
Original line number Diff line number Diff line
@@ -3107,7 +3107,9 @@ smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses, 
						struct cifs_tcon,

						tcon_list);

		if (tcon) {

			spin_lock(&tcon->tc_lock);

			tcon->tc_count++;

			spin_unlock(&tcon->tc_lock);

			trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,

					    netfs_trace_tcon_ref_get_dfs_refer);

		}
@@ -3176,13 +3178,9 @@ smb2_get_dfs_refer(const unsigned int xid, struct cifs_ses *ses, 
 out:

	if (tcon && !tcon->ipc) {

		/* ipc tcons are not refcounted */

		spin_lock(&cifs_tcp_ses_lock);

		tcon->tc_count--;

		cifs_put_tcon(tcon, netfs_trace_tcon_ref_put_dfs_refer);

		trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,

				    netfs_trace_tcon_ref_dec_dfs_refer);

		/* tc_count can never go negative */

		WARN_ON(tcon->tc_count < 0);

		spin_unlock(&cifs_tcp_ses_lock);

	}

	kfree(utf16_path);

	kfree(dfs_req);

fs/smb/client/smb2pdu.c

+2 −0
Original line number Diff line number Diff line
@@ -4263,7 +4263,9 @@ void smb2_reconnect_server(struct work_struct *work) 


		list_for_each_entry(tcon, &ses->tcon_list, tcon_list) {

			if (tcon->need_reconnect || tcon->need_reopen_files) {

				spin_lock(&tcon->tc_lock);

				tcon->tc_count++;

				spin_unlock(&tcon->tc_lock);

				trace_smb3_tcon_ref(tcon->debug_id, tcon->tc_count,

						    netfs_trace_tcon_ref_get_reconnect_server);

				list_add_tail(&tcon->rlist, &tmp_list);

fs/smb/client/trace.h

+1 −0
Original line number Diff line number Diff line
@@ -189,6 +189,7 @@ 
	EM(netfs_trace_tcon_ref_put_cancelled_close_fid, "PUT Cn-Fid") \

	EM(netfs_trace_tcon_ref_put_cancelled_mid,	"PUT Cn-Mid") \

	EM(netfs_trace_tcon_ref_put_mnt_ctx,		"PUT MntCtx") \

	EM(netfs_trace_tcon_ref_put_dfs_refer,		"PUT DfsRfr") \

	EM(netfs_trace_tcon_ref_put_reconnect_server,	"PUT Reconn") \

	EM(netfs_trace_tcon_ref_put_tlink,		"PUT Tlink ") \

	EM(netfs_trace_tcon_ref_see_cancelled_close,	"SEE Cn-Cls") \