Commit 5752bf64 authored by Shyam Prasad N's avatar Shyam Prasad N Committed by Steve French
Browse files

cifs: avoid parallel session setups on same channel 



After allowing channels to reconnect in parallel, it now
becomes important to take care that multiple processes do not
call negotiate/session setup in parallel on the same channel.

This change avoids that by marking a channel as "in_reconnect".
During session setup if the channel in question has this flag
set, we return immediately.

Signed-off-by: default avatarShyam Prasad N <sprasad@microsoft.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent dd3cd870

fs/cifs/cifs_debug.c

+4 −0
Original line number Diff line number Diff line
@@ -419,6 +419,8 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v) 
			spin_lock(&ses->chan_lock);

			if (CIFS_CHAN_NEEDS_RECONNECT(ses, 0))

				seq_puts(m, "\tPrimary channel: DISCONNECTED ");

			if (CIFS_CHAN_IN_RECONNECT(ses, 0))

				seq_puts(m, "\t[RECONNECTING] ");



			if (ses->chan_count > 1) {

				seq_printf(m, "\n\n\tExtra Channels: %zu ",
@@ -427,6 +429,8 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v) 
					cifs_dump_channel(m, j, &ses->chans[j]);

					if (CIFS_CHAN_NEEDS_RECONNECT(ses, j))

						seq_puts(m, "\tDISCONNECTED ");

					if (CIFS_CHAN_IN_RECONNECT(ses, j))

						seq_puts(m, "\t[RECONNECTING] ");

				}

			}

			spin_unlock(&ses->chan_lock);

fs/cifs/cifsglob.h

+5 −0
Original line number Diff line number Diff line
@@ -922,6 +922,7 @@ struct cifs_server_iface { 
};



struct cifs_chan {

	unsigned int in_reconnect : 1; /* if session setup in progress for this channel */

	struct TCP_Server_Info *server;

	__u8 signkey[SMB3_SIGN_KEY_SIZE];

};
@@ -984,12 +985,16 @@ struct cifs_ses { 
#define CIFS_MAX_CHANNELS 16

#define CIFS_ALL_CHANNELS_SET(ses)	\

	((1UL << (ses)->chan_count) - 1)

#define CIFS_ALL_CHANS_GOOD(ses)		\

	(!(ses)->chans_need_reconnect)

#define CIFS_ALL_CHANS_NEED_RECONNECT(ses)	\

	((ses)->chans_need_reconnect == CIFS_ALL_CHANNELS_SET(ses))

#define CIFS_SET_ALL_CHANS_NEED_RECONNECT(ses)	\

	((ses)->chans_need_reconnect = CIFS_ALL_CHANNELS_SET(ses))

#define CIFS_CHAN_NEEDS_RECONNECT(ses, index)	\

	test_bit((index), &(ses)->chans_need_reconnect)

#define CIFS_CHAN_IN_RECONNECT(ses, index)	\

	((ses)->chans[(index)].in_reconnect)



	struct cifs_chan chans[CIFS_MAX_CHANNELS];

	size_t chan_count;

fs/cifs/cifsproto.h

+9 −0
Original line number Diff line number Diff line
@@ -619,6 +619,15 @@ unsigned int 
cifs_ses_get_chan_index(struct cifs_ses *ses,

			struct TCP_Server_Info *server);

void

cifs_chan_set_in_reconnect(struct cifs_ses *ses,

			     struct TCP_Server_Info *server);

void

cifs_chan_clear_in_reconnect(struct cifs_ses *ses,

			       struct TCP_Server_Info *server);

bool

cifs_chan_in_reconnect(struct cifs_ses *ses,

			  struct TCP_Server_Info *server);

void

cifs_chan_set_need_reconnect(struct cifs_ses *ses,

			     struct TCP_Server_Info *server);

void

fs/cifs/connect.c

+20 −7
Original line number Diff line number Diff line
@@ -3995,16 +3995,26 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses, 
	int rc = -ENOSYS;

	bool is_binding = false;





	spin_lock(&cifs_tcp_ses_lock);

	if (ses->ses_status != SES_GOOD &&

	    ses->ses_status != SES_NEW &&

	    ses->ses_status != SES_NEED_RECON) {

		spin_unlock(&cifs_tcp_ses_lock);

		return 0;

	}



	/* only send once per connect */

	spin_lock(&ses->chan_lock);

	is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);

	if (CIFS_ALL_CHANS_GOOD(ses) ||

	    cifs_chan_in_reconnect(ses, server)) {

		spin_unlock(&ses->chan_lock);



	spin_lock(&cifs_tcp_ses_lock);

	if (ses->ses_status == SES_EXITING) {

		spin_unlock(&cifs_tcp_ses_lock);

		return 0;

	}

	is_binding = !CIFS_ALL_CHANS_NEED_RECONNECT(ses);

	cifs_chan_set_in_reconnect(ses, server);

	spin_unlock(&ses->chan_lock);



	if (!is_binding)

		ses->ses_status = SES_IN_SETUP;
@@ -4035,16 +4045,19 @@ cifs_setup_session(const unsigned int xid, struct cifs_ses *ses, 
		spin_lock(&cifs_tcp_ses_lock);

		if (ses->ses_status == SES_IN_SETUP)

			ses->ses_status = SES_NEED_RECON;

		spin_lock(&ses->chan_lock);

		cifs_chan_clear_in_reconnect(ses, server);

		spin_unlock(&ses->chan_lock);

		spin_unlock(&cifs_tcp_ses_lock);

	} else {

		spin_lock(&cifs_tcp_ses_lock);

		if (ses->ses_status == SES_IN_SETUP)

			ses->ses_status = SES_GOOD;

		spin_unlock(&cifs_tcp_ses_lock);



		spin_lock(&ses->chan_lock);

		cifs_chan_clear_in_reconnect(ses, server);

		cifs_chan_clear_need_reconnect(ses, server);

		spin_unlock(&ses->chan_lock);

		spin_unlock(&cifs_tcp_ses_lock);

	}



	return rc;

fs/cifs/sess.c

+27 −0
Original line number Diff line number Diff line
@@ -85,6 +85,33 @@ cifs_ses_get_chan_index(struct cifs_ses *ses, 
	return 0;

}



void

cifs_chan_set_in_reconnect(struct cifs_ses *ses,

			     struct TCP_Server_Info *server)

{

	unsigned int chan_index = cifs_ses_get_chan_index(ses, server);



	ses->chans[chan_index].in_reconnect = true;

}



void

cifs_chan_clear_in_reconnect(struct cifs_ses *ses,

			     struct TCP_Server_Info *server)

{

	unsigned int chan_index = cifs_ses_get_chan_index(ses, server);



	ses->chans[chan_index].in_reconnect = false;

}



bool

cifs_chan_in_reconnect(struct cifs_ses *ses,

			  struct TCP_Server_Info *server)

{

	unsigned int chan_index = cifs_ses_get_chan_index(ses, server);



	return CIFS_CHAN_IN_RECONNECT(ses, chan_index);

}



void

cifs_chan_set_need_reconnect(struct cifs_ses *ses,

			     struct TCP_Server_Info *server)