On Wed, Sep 29, 2010 at 2:27 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote:
> cifs_reconnect_tcon is called from smb_init. After a successful
> reconnect, cifs_reconnect_tcon will call reset_cifs_unix_caps. That
> function will, in turn call CIFSSMBQFSUnixInfo and CIFSSMBSetFSUnixInfo.
> Those functions also call smb_init.
>
> It's possible for the session and tcon reconnect to succeed, and then
> for another cifs_reconnect to occur before CIFSSMBQFSUnixInfo or
> CIFSSMBSetFSUnixInfo to be called. That'll cause those functions to call
> smb_init and cifs_reconnect_tcon again, ad infinitum...
>
> Break the infinite recursion by having those functions use a new
> smb_init variant that doesn't attempt to perform a reconnect.
>
> Reported-and-Tested-by: Michal Suchanek <hramrach@xxxxxxxxxx>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/cifs/cifssmb.c | 49 +++++++++++++++++++++++++++++++++----------------
> 1 files changed, 33 insertions(+), 16 deletions(-)
>
> diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
> index 13c854e..54bd83a 100644
> --- a/fs/cifs/cifssmb.c
> +++ b/fs/cifs/cifssmb.c
> @@ -232,7 +232,7 @@ static int
> small_smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
> void **request_buf)
> {
> - int rc = 0;
> + int rc;
>
> rc = cifs_reconnect_tcon(tcon, smb_command);
> if (rc)
> @@ -250,7 +250,7 @@ small_smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
> if (tcon != NULL)
> cifs_stats_inc(&tcon->num_smbs_sent);
>
> - return rc;
> + return 0;
> }
>
> int
> @@ -281,16 +281,9 @@ small_smb_init_no_tc(const int smb_command, const int wct,
>
> /* If the return code is zero, this function must fill in request_buf pointer */
> static int
> -smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
> - void **request_buf /* returned */ ,
> - void **response_buf /* returned */ )
> +__smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
> + void **request_buf, void **response_buf)
> {
> - int rc = 0;
> -
> - rc = cifs_reconnect_tcon(tcon, smb_command);
> - if (rc)
> - return rc;
> -
> *request_buf = cifs_buf_get();
> if (*request_buf == NULL) {
> /* BB should we add a retry in here if not a writepage? */
> @@ -309,7 +302,31 @@ smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
> if (tcon != NULL)
> cifs_stats_inc(&tcon->num_smbs_sent);
>
> - return rc;
> + return 0;
> +}
> +
> +/* If the return code is zero, this function must fill in request_buf pointer */
> +static int
> +smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
> + void **request_buf, void **response_buf)
> +{
> + int rc;
> +
> + rc = cifs_reconnect_tcon(tcon, smb_command);
> + if (rc)
> + return rc;
> +
> + return __smb_init(smb_command, wct, tcon, request_buf, response_buf);
> +}
> +
> +static int
> +smb_init_no_reconnect(int smb_command, int wct, struct cifsTconInfo *tcon,
> + void **request_buf, void **response_buf)
> +{
> + if (tcon->ses->need_reconnect || tcon->need_reconnect)
> + return -EHOSTDOWN;
> +
> + return __smb_init(smb_command, wct, tcon, request_buf, response_buf);
> }
>
> static int validate_t2(struct smb_t2_rsp *pSMB)
> @@ -4536,8 +4553,8 @@ CIFSSMBQFSUnixInfo(const int xid, struct cifsTconInfo *tcon)
>
> cFYI(1, "In QFSUnixInfo");
> QFSUnixRetry:
> - rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB,
> - (void **) &pSMBr);
> + rc = smb_init_no_reconnect(SMB_COM_TRANSACTION2, 15, tcon,
> + (void **) &pSMB, (void **) &pSMBr);
> if (rc)
> return rc;
>
> @@ -4606,8 +4623,8 @@ CIFSSMBSetFSUnixInfo(const int xid, struct cifsTconInfo *tcon, __u64 cap)
> cFYI(1, "In SETFSUnixInfo");
> SETFSUnixRetry:
> /* BB switch to small buf init to save memory */
> - rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB,
> - (void **) &pSMBr);
> + rc = smb_init_no_reconnect(SMB_COM_TRANSACTION2, 15, tcon,
> + (void **) &pSMB, (void **) &pSMBr);
> if (rc)
> return rc;
>
> --
> 1.7.2.3
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-cifs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
Jeff, is same code change is needed in non-unix versions of these functions
such as CIFSSMBQFSInfo?
--
To unsubscribe from this list: send the line "unsubscribe linux-cifs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
