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cifs: allow for different handling of received response
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In order to incorporate async requests, we need to allow for a more
general way to do things on receive, rather than just waking up a
process.

Turn the task pointer in the mid_q_entry into a callback function and a
generic data pointer. When a response comes in, or the socket is
reconnected, cifsd can call the callback function in order to wake up
the process.

The default is to just wake up the current process which should mean no
change in behavior for existing code.

Also, clean up the locking in cifs_reconnect. There doesn't seem to be
any need to hold both the srv_mutex and GlobalMid_Lock when walking the
list of mids.

Reviewed-by: Suresh Jayaraman <sjayaraman@suse.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
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Jeff Layton authored and Steve French committed Jan 20, 2011
1 parent 74dd92a commit 2b84a36
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Showing 4 changed files with 60 additions and 35 deletions.
8 changes: 4 additions & 4 deletions fs/cifs/cifs_debug.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -79,11 +79,11 @@ void cifs_dump_mids(struct TCP_Server_Info *server)
spin_lock(&GlobalMid_Lock);
list_for_each(tmp, &server->pending_mid_q) {
mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
cERROR(1, "State: %d Cmd: %d Pid: %d Tsk: %p Mid %d",
cERROR(1, "State: %d Cmd: %d Pid: %d Cbdata: %p Mid %d",
mid_entry->midState,
(int)mid_entry->command,
mid_entry->pid,
mid_entry->tsk,
mid_entry->callback_data,
mid_entry->mid);
#ifdef CONFIG_CIFS_STATS2
cERROR(1, "IsLarge: %d buf: %p time rcv: %ld now: %ld",
Expand Down Expand Up @@ -218,11 +218,11 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
mid_entry = list_entry(tmp3, struct mid_q_entry,
qhead);
seq_printf(m, "\tState: %d com: %d pid:"
" %d tsk: %p mid %d\n",
" %d cbdata: %p mid %d\n",
mid_entry->midState,
(int)mid_entry->command,
mid_entry->pid,
mid_entry->tsk,
mid_entry->callback_data,
mid_entry->mid);
}
spin_unlock(&GlobalMid_Lock);
Expand Down
15 changes: 14 additions & 1 deletion fs/cifs/cifsglob.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -508,6 +508,18 @@ static inline void cifs_stats_bytes_read(struct cifsTconInfo *tcon,

#endif

struct mid_q_entry;

/*
* This is the prototype for the mid callback function. When creating one,
* take special care to avoid deadlocks. Things to bear in mind:
*
* - it will be called by cifsd
* - the GlobalMid_Lock will be held
* - the mid will be removed from the pending_mid_q list
*/
typedef void (mid_callback_t)(struct mid_q_entry *mid);

/* one of these for every pending CIFS request to the server */
struct mid_q_entry {
struct list_head qhead; /* mids waiting on reply from this server */
Expand All @@ -519,7 +531,8 @@ struct mid_q_entry {
unsigned long when_sent; /* time when smb send finished */
unsigned long when_received; /* when demux complete (taken off wire) */
#endif
struct task_struct *tsk; /* task waiting for response */
mid_callback_t *callback; /* call completion callback */
void *callback_data; /* general purpose pointer for callback */
struct smb_hdr *resp_buf; /* response buffer */
int midState; /* wish this were enum but can not pass to wait_event */
__u8 command; /* smb command code */
Expand Down
53 changes: 25 additions & 28 deletions fs/cifs/connect.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -152,6 +152,7 @@ cifs_reconnect(struct TCP_Server_Info *server)

/* before reconnecting the tcp session, mark the smb session (uid)
and the tid bad so they are not used until reconnected */
cFYI(1, "%s: marking sessions and tcons for reconnect", __func__);
spin_lock(&cifs_tcp_ses_lock);
list_for_each(tmp, &server->smb_ses_list) {
ses = list_entry(tmp, struct cifsSesInfo, smb_ses_list);
Expand All @@ -163,7 +164,9 @@ cifs_reconnect(struct TCP_Server_Info *server)
}
}
spin_unlock(&cifs_tcp_ses_lock);

/* do not want to be sending data on a socket we are freeing */
cFYI(1, "%s: tearing down socket", __func__);
mutex_lock(&server->srv_mutex);
if (server->ssocket) {
cFYI(1, "State: 0x%x Flags: 0x%lx", server->ssocket->state,
Expand All @@ -180,22 +183,19 @@ cifs_reconnect(struct TCP_Server_Info *server)
kfree(server->session_key.response);
server->session_key.response = NULL;
server->session_key.len = 0;
mutex_unlock(&server->srv_mutex);

/* mark submitted MIDs for retry and issue callback */
cFYI(1, "%s: issuing mid callbacks", __func__);
spin_lock(&GlobalMid_Lock);
list_for_each(tmp, &server->pending_mid_q) {
mid_entry = list_entry(tmp, struct
mid_q_entry,
qhead);
if (mid_entry->midState == MID_REQUEST_SUBMITTED) {
/* Mark other intransit requests as needing
retry so we do not immediately mark the
session bad again (ie after we reconnect
below) as they timeout too */
list_for_each_safe(tmp, tmp2, &server->pending_mid_q) {
mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
if (mid_entry->midState == MID_REQUEST_SUBMITTED)
mid_entry->midState = MID_RETRY_NEEDED;
}
list_del_init(&mid_entry->qhead);
mid_entry->callback(mid_entry);
}
spin_unlock(&GlobalMid_Lock);
mutex_unlock(&server->srv_mutex);

while ((server->tcpStatus != CifsExiting) &&
(server->tcpStatus != CifsGood)) {
Expand All @@ -212,10 +212,9 @@ cifs_reconnect(struct TCP_Server_Info *server)
if (server->tcpStatus != CifsExiting)
server->tcpStatus = CifsGood;
spin_unlock(&GlobalMid_Lock);
/* atomic_set(&server->inFlight,0);*/
wake_up(&server->response_q);
}
}

return rc;
}

Expand Down Expand Up @@ -345,7 +344,7 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
struct msghdr smb_msg;
struct kvec iov;
struct socket *csocket = server->ssocket;
struct list_head *tmp;
struct list_head *tmp, *tmp2;
struct task_struct *task_to_wake = NULL;
struct mid_q_entry *mid_entry;
char temp;
Expand Down Expand Up @@ -558,10 +557,9 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
continue;
}


task_to_wake = NULL;
mid_entry = NULL;
spin_lock(&GlobalMid_Lock);
list_for_each(tmp, &server->pending_mid_q) {
list_for_each_safe(tmp, tmp2, &server->pending_mid_q) {
mid_entry = list_entry(tmp, struct mid_q_entry, qhead);

if ((mid_entry->mid == smb_buffer->Mid) &&
Expand Down Expand Up @@ -602,8 +600,9 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
mid_entry->resp_buf = smb_buffer;
mid_entry->largeBuf = isLargeBuf;
multi_t2_fnd:
task_to_wake = mid_entry->tsk;
mid_entry->midState = MID_RESPONSE_RECEIVED;
list_del_init(&mid_entry->qhead);
mid_entry->callback(mid_entry);
#ifdef CONFIG_CIFS_STATS2
mid_entry->when_received = jiffies;
#endif
Expand All @@ -613,9 +612,11 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
server->lstrp = jiffies;
break;
}
mid_entry = NULL;
}
spin_unlock(&GlobalMid_Lock);
if (task_to_wake) {

if (mid_entry != NULL) {
/* Was previous buf put in mpx struct for multi-rsp? */
if (!isMultiRsp) {
/* smb buffer will be freed by user thread */
Expand All @@ -624,7 +625,6 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)
else
smallbuf = NULL;
}
wake_up_process(task_to_wake);
} else if (!is_valid_oplock_break(smb_buffer, server) &&
!isMultiRsp) {
cERROR(1, "No task to wake, unknown frame received! "
Expand Down Expand Up @@ -678,15 +678,12 @@ cifs_demultiplex_thread(struct TCP_Server_Info *server)

if (!list_empty(&server->pending_mid_q)) {
spin_lock(&GlobalMid_Lock);
list_for_each(tmp, &server->pending_mid_q) {
list_for_each_safe(tmp, tmp2, &server->pending_mid_q) {
mid_entry = list_entry(tmp, struct mid_q_entry, qhead);
if (mid_entry->midState == MID_REQUEST_SUBMITTED) {
cFYI(1, "Clearing Mid 0x%x - waking up ",
mid_entry->mid);
task_to_wake = mid_entry->tsk;
if (task_to_wake)
wake_up_process(task_to_wake);
}
cFYI(1, "Clearing Mid 0x%x - issuing callback",
mid_entry->mid);
list_del_init(&mid_entry->qhead);
mid_entry->callback(mid_entry);
}
spin_unlock(&GlobalMid_Lock);
/* 1/8th of sec is more than enough time for them to exit */
Expand Down
19 changes: 17 additions & 2 deletions fs/cifs/transport.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,12 @@

extern mempool_t *cifs_mid_poolp;

static void
wake_up_task(struct mid_q_entry *mid)
{
wake_up_process(mid->callback_data);
}

static struct mid_q_entry *
AllocMidQEntry(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
{
Expand All @@ -58,7 +64,13 @@ AllocMidQEntry(const struct smb_hdr *smb_buffer, struct TCP_Server_Info *server)
/* do_gettimeofday(&temp->when_sent);*/ /* easier to use jiffies */
/* when mid allocated can be before when sent */
temp->when_alloc = jiffies;
temp->tsk = current;

/*
* The default is for the mid to be synchronous, so the
* default callback just wakes up the current task.
*/
temp->callback = wake_up_task;
temp->callback_data = current;
}

atomic_inc(&midCount);
Expand Down Expand Up @@ -367,6 +379,9 @@ sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
mid->mid, mid->midState);

spin_lock(&GlobalMid_Lock);
/* ensure that it's no longer on the pending_mid_q */
list_del_init(&mid->qhead);

switch (mid->midState) {
case MID_RESPONSE_RECEIVED:
spin_unlock(&GlobalMid_Lock);
Expand All @@ -389,7 +404,7 @@ sync_mid_result(struct mid_q_entry *mid, struct TCP_Server_Info *server)
}
spin_unlock(&GlobalMid_Lock);

delete_mid(mid);
DeleteMidQEntry(mid);
return rc;
}

Expand Down

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