Commit 3a7b6d0a authored by David Howells's avatar David Howells Committed by Steve French
Browse files

cifs: Don't need state locking in smb2_get_mid_entry() 



There's no need to get ->srv_lock or ->ses_lock in smb2_get_mid_entry() as
all that happens of relevance (to the lock) inside the locked sections is
the reading of one status value in each.

Replace the locking with READ_ONCE() and use a switch instead of a chain of
if-statements.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
Reviewed-by: default avatarPaulo Alcantara (Red Hat) <pc@manguebit.org>
cc: Shyam Prasad N <sprasad@microsoft.com>
cc: Tom Talpey <tom@talpey.com>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 87fba18a

fs/smb/client/smb2transport.c

+20 −28
Original line number Diff line number Diff line
@@ -684,43 +684,35 @@ static int 
smb2_get_mid_entry(struct cifs_ses *ses, struct TCP_Server_Info *server,

		   struct smb2_hdr *shdr, struct mid_q_entry **mid)

{

	spin_lock(&server->srv_lock);

	if (server->tcpStatus == CifsExiting) {

		spin_unlock(&server->srv_lock);

	switch (READ_ONCE(server->tcpStatus)) {

	case CifsExiting:

		return -ENOENT;

	}



	if (server->tcpStatus == CifsNeedReconnect) {

		spin_unlock(&server->srv_lock);

	case CifsNeedReconnect:

		cifs_dbg(FYI, "tcp session dead - return to caller to retry\n");

		return -EAGAIN;

	}



	if (server->tcpStatus == CifsNeedNegotiate &&

	   shdr->Command != SMB2_NEGOTIATE) {

		spin_unlock(&server->srv_lock);

	case CifsNeedNegotiate:

		if (shdr->Command != SMB2_NEGOTIATE)

			return -EAGAIN;

		break;

	default:

		break;

	}

	spin_unlock(&server->srv_lock);



	spin_lock(&ses->ses_lock);

	if (ses->ses_status == SES_NEW) {

		if ((shdr->Command != SMB2_SESSION_SETUP) &&

		    (shdr->Command != SMB2_NEGOTIATE)) {

			spin_unlock(&ses->ses_lock);

	switch (READ_ONCE(ses->ses_status)) {

	case SES_NEW:

		if (shdr->Command != SMB2_SESSION_SETUP &&

		    shdr->Command != SMB2_NEGOTIATE)

			return -EAGAIN;

		}

			/* else ok - we are setting up session */

	}



	if (ses->ses_status == SES_EXITING) {

		if (shdr->Command != SMB2_LOGOFF) {

			spin_unlock(&ses->ses_lock);

		break;

	case SES_EXITING:

		if (shdr->Command != SMB2_LOGOFF)

			return -EAGAIN;

		}

		/* else ok - we are shutting down the session */

		break;

	default:

		break;

	}

	spin_unlock(&ses->ses_lock);



	*mid = smb2_mid_entry_alloc(shdr, server);

	if (*mid == NULL)