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

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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: David Howells <dhowells@redhat.com>
Reviewed-by: Paulo 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: Steve French <stfrench@microsoft.com>
This commit is contained in:
David Howells 2025-08-04 09:38:21 +01:00 committed by Steve French
parent 87fba18abb
commit 3a7b6d0afe
1 changed files with 20 additions and 28 deletions
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48
fs/smb/client/smb2transport.c
View File

@ -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);
return -EAGAIN;
}
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);
case CifsNeedNegotiate:
if (shdr->Command != SMB2_NEGOTIATE)
return -EAGAIN;
}
/* else ok - we are setting up session */
break;
default:
break;
}
if (ses->ses_status == SES_EXITING) {
if (shdr->Command != SMB2_LOGOFF) {
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 */
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)