[PATCH] v9fs: signal handling fixes
Multiple races can happen when v9fs is interrupted by a signal and Tflush
message is sent to the server. After v9fs sends Tflush it doesn't wait
until it receives Rflush, and possibly the response of the original
message. This behavior may confuse v9fs what fids are allocated by the
file server.
This patch fixes the races and the fid allocation.
Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Cc: Eric Van Hensbergen <ericvh@hera.kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/9p/mux.c b/fs/9p/mux.c
index 3e5b124..f4407eb 100644
--- a/fs/9p/mux.c
+++ b/fs/9p/mux.c
@@ -50,15 +50,23 @@
Wpending = 8, /* can write */
};
+enum {
+ None,
+ Flushing,
+ Flushed,
+};
+
struct v9fs_mux_poll_task;
struct v9fs_req {
+ spinlock_t lock;
int tag;
struct v9fs_fcall *tcall;
struct v9fs_fcall *rcall;
int err;
v9fs_mux_req_callback cb;
void *cba;
+ int flush;
struct list_head req_list;
};
@@ -96,8 +104,8 @@
struct v9fs_mux_rpc {
struct v9fs_mux_data *m;
- struct v9fs_req *req;
int err;
+ struct v9fs_fcall *tcall;
struct v9fs_fcall *rcall;
wait_queue_head_t wqueue;
};
@@ -524,10 +532,9 @@
static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req)
{
- int ecode, tag;
+ int ecode;
struct v9fs_str *ename;
- tag = req->tag;
if (!req->err && req->rcall->id == RERROR) {
ecode = req->rcall->params.rerror.errno;
ename = &req->rcall->params.rerror.error;
@@ -553,23 +560,6 @@
if (!req->err)
req->err = -EIO;
}
-
- if (req->err == ERREQFLUSH)
- return;
-
- if (req->cb) {
- dprintk(DEBUG_MUX, "calling callback tcall %p rcall %p\n",
- req->tcall, req->rcall);
-
- (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
- req->cb = NULL;
- } else
- kfree(req->rcall);
-
- v9fs_mux_put_tag(m, tag);
-
- wake_up(&m->equeue);
- kfree(req);
}
/**
@@ -669,17 +659,26 @@
list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
if (rreq->tag == rcall->tag) {
req = rreq;
- req->rcall = rcall;
- list_del(&req->req_list);
- spin_unlock(&m->lock);
- process_request(m, req);
+ if (req->flush != Flushing)
+ list_del(&req->req_list);
break;
}
-
}
+ spin_unlock(&m->lock);
- if (!req) {
- spin_unlock(&m->lock);
+ if (req) {
+ req->rcall = rcall;
+ process_request(m, req);
+
+ if (req->flush != Flushing) {
+ if (req->cb)
+ (*req->cb) (req, req->cba);
+ else
+ kfree(req->rcall);
+
+ wake_up(&m->equeue);
+ }
+ } else {
if (err >= 0 && rcall->id != RFLUSH)
dprintk(DEBUG_ERROR,
"unexpected response mux %p id %d tag %d\n",
@@ -746,7 +745,6 @@
return ERR_PTR(-ENOMEM);
v9fs_set_tag(tc, n);
-
if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
char buf[150];
@@ -754,12 +752,14 @@
printk(KERN_NOTICE "<<< %p %s\n", m, buf);
}
+ spin_lock_init(&req->lock);
req->tag = n;
req->tcall = tc;
req->rcall = NULL;
req->err = 0;
req->cb = cb;
req->cba = cba;
+ req->flush = None;
spin_lock(&m->lock);
list_add_tail(&req->req_list, &m->unsent_req_list);
@@ -776,72 +776,108 @@
return req;
}
-static void v9fs_mux_flush_cb(void *a, struct v9fs_fcall *tc,
- struct v9fs_fcall *rc, int err)
+static void v9fs_mux_free_request(struct v9fs_mux_data *m, struct v9fs_req *req)
+{
+ v9fs_mux_put_tag(m, req->tag);
+ kfree(req);
+}
+
+static void v9fs_mux_flush_cb(struct v9fs_req *freq, void *a)
{
v9fs_mux_req_callback cb;
int tag;
struct v9fs_mux_data *m;
- struct v9fs_req *req, *rptr;
+ struct v9fs_req *req, *rreq, *rptr;
m = a;
- dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m, tc,
- rc, err, tc->params.tflush.oldtag);
+ dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
+ freq->tcall, freq->rcall, freq->err,
+ freq->tcall->params.tflush.oldtag);
spin_lock(&m->lock);
cb = NULL;
- tag = tc->params.tflush.oldtag;
- list_for_each_entry_safe(req, rptr, &m->req_list, req_list) {
- if (req->tag == tag) {
+ tag = freq->tcall->params.tflush.oldtag;
+ req = NULL;
+ list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
+ if (rreq->tag == tag) {
+ req = rreq;
list_del(&req->req_list);
- if (req->cb) {
- cb = req->cb;
- req->cb = NULL;
- spin_unlock(&m->lock);
- (*cb) (req->cba, req->tcall, req->rcall,
- req->err);
- }
- kfree(req);
- wake_up(&m->equeue);
break;
}
}
+ spin_unlock(&m->lock);
- if (!cb)
- spin_unlock(&m->lock);
+ if (req) {
+ spin_lock(&req->lock);
+ req->flush = Flushed;
+ spin_unlock(&req->lock);
- v9fs_mux_put_tag(m, tag);
- kfree(tc);
- kfree(rc);
+ if (req->cb)
+ (*req->cb) (req, req->cba);
+ else
+ kfree(req->rcall);
+
+ wake_up(&m->equeue);
+ }
+
+ kfree(freq->tcall);
+ kfree(freq->rcall);
+ v9fs_mux_free_request(m, freq);
}
-static void
+static int
v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
{
struct v9fs_fcall *fc;
+ struct v9fs_req *rreq, *rptr;
dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
+ /* if a response was received for a request, do nothing */
+ spin_lock(&req->lock);
+ if (req->rcall || req->err) {
+ spin_unlock(&req->lock);
+ dprintk(DEBUG_MUX, "mux %p req %p response already received\n", m, req);
+ return 0;
+ }
+
+ req->flush = Flushing;
+ spin_unlock(&req->lock);
+
+ spin_lock(&m->lock);
+ /* if the request is not sent yet, just remove it from the list */
+ list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
+ if (rreq->tag == req->tag) {
+ dprintk(DEBUG_MUX, "mux %p req %p request is not sent yet\n", m, req);
+ list_del(&rreq->req_list);
+ req->flush = Flushed;
+ spin_unlock(&m->lock);
+ if (req->cb)
+ (*req->cb) (req, req->cba);
+ return 0;
+ }
+ }
+ spin_unlock(&m->lock);
+
+ clear_thread_flag(TIF_SIGPENDING);
fc = v9fs_create_tflush(req->tag);
v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
+ return 1;
}
static void
-v9fs_mux_rpc_cb(void *a, struct v9fs_fcall *tc, struct v9fs_fcall *rc, int err)
+v9fs_mux_rpc_cb(struct v9fs_req *req, void *a)
{
struct v9fs_mux_rpc *r;
- if (err == ERREQFLUSH) {
- kfree(rc);
- dprintk(DEBUG_MUX, "err req flush\n");
- return;
- }
-
+ dprintk(DEBUG_MUX, "req %p r %p\n", req, a);
r = a;
- dprintk(DEBUG_MUX, "mux %p req %p tc %p rc %p err %d\n", r->m, r->req,
- tc, rc, err);
- r->rcall = rc;
- r->err = err;
+ r->rcall = req->rcall;
+ r->err = req->err;
+
+ if (req->flush!=None && !req->err)
+ r->err = -ERESTARTSYS;
+
wake_up(&r->wqueue);
}
@@ -856,12 +892,13 @@
v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
struct v9fs_fcall **rc)
{
- int err;
+ int err, sigpending;
unsigned long flags;
struct v9fs_req *req;
struct v9fs_mux_rpc r;
r.err = 0;
+ r.tcall = tc;
r.rcall = NULL;
r.m = m;
init_waitqueue_head(&r.wqueue);
@@ -869,48 +906,50 @@
if (rc)
*rc = NULL;
+ sigpending = 0;
+ if (signal_pending(current)) {
+ sigpending = 1;
+ clear_thread_flag(TIF_SIGPENDING);
+ }
+
req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
if (IS_ERR(req)) {
err = PTR_ERR(req);
dprintk(DEBUG_MUX, "error %d\n", err);
- return PTR_ERR(req);
+ return err;
}
- r.req = req;
- dprintk(DEBUG_MUX, "mux %p tc %p tag %d rpc %p req %p\n", m, tc,
- req->tag, &r, req);
err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
if (r.err < 0)
err = r.err;
if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
- spin_lock(&m->lock);
- req->tcall = NULL;
- req->err = ERREQFLUSH;
- spin_unlock(&m->lock);
+ if (v9fs_mux_flush_request(m, req)) {
+ /* wait until we get response of the flush message */
+ do {
+ clear_thread_flag(TIF_SIGPENDING);
+ err = wait_event_interruptible(r.wqueue,
+ r.rcall || r.err);
+ } while (!r.rcall && !r.err && err==-ERESTARTSYS &&
+ m->trans->status==Connected && !m->err);
+ }
+ sigpending = 1;
+ }
- clear_thread_flag(TIF_SIGPENDING);
- v9fs_mux_flush_request(m, req);
+ if (sigpending) {
spin_lock_irqsave(¤t->sighand->siglock, flags);
recalc_sigpending();
spin_unlock_irqrestore(¤t->sighand->siglock, flags);
}
- if (!err) {
- if (r.rcall)
- dprintk(DEBUG_MUX, "got response id %d tag %d\n",
- r.rcall->id, r.rcall->tag);
-
- if (rc)
- *rc = r.rcall;
- else
- kfree(r.rcall);
- } else {
+ if (rc)
+ *rc = r.rcall;
+ else
kfree(r.rcall);
- dprintk(DEBUG_MUX, "got error %d\n", err);
- if (err > 0)
- err = -EIO;
- }
+
+ v9fs_mux_free_request(m, req);
+ if (err > 0)
+ err = -EIO;
return err;
}
@@ -951,12 +990,15 @@
struct v9fs_req *req, *rtmp;
LIST_HEAD(cancel_list);
- dprintk(DEBUG_MUX, "mux %p err %d\n", m, err);
+ dprintk(DEBUG_ERROR, "mux %p err %d\n", m, err);
m->err = err;
spin_lock(&m->lock);
list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
list_move(&req->req_list, &cancel_list);
}
+ list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
+ list_move(&req->req_list, &cancel_list);
+ }
spin_unlock(&m->lock);
list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
@@ -965,11 +1007,9 @@
req->err = err;
if (req->cb)
- (*req->cb) (req->cba, req->tcall, req->rcall, req->err);
+ (*req->cb) (req, req->cba);
else
kfree(req->rcall);
-
- kfree(req);
}
wake_up(&m->equeue);
diff --git a/fs/9p/mux.h b/fs/9p/mux.h
index e90bfd3..fb10c50 100644
--- a/fs/9p/mux.h
+++ b/fs/9p/mux.h
@@ -24,6 +24,7 @@
*/
struct v9fs_mux_data;
+struct v9fs_req;
/**
* v9fs_mux_req_callback - callback function that is called when the
@@ -36,8 +37,7 @@
* @rc - response call
* @err - error code (non-zero if error occured)
*/
-typedef void (*v9fs_mux_req_callback)(void *a, struct v9fs_fcall *tc,
- struct v9fs_fcall *rc, int err);
+typedef void (*v9fs_mux_req_callback)(struct v9fs_req *req, void *a);
int v9fs_mux_global_init(void);
void v9fs_mux_global_exit(void);
diff --git a/fs/9p/vfs_file.c b/fs/9p/vfs_file.c
index 083dcfc..1a8e460 100644
--- a/fs/9p/vfs_file.c
+++ b/fs/9p/vfs_file.c
@@ -72,11 +72,17 @@
return -ENOSPC;
}
- err = v9fs_t_walk(v9ses, vfid->fid, fid, NULL, NULL);
+ err = v9fs_t_walk(v9ses, vfid->fid, fid, NULL, &fcall);
if (err < 0) {
dprintk(DEBUG_ERROR, "rewalk didn't work\n");
- goto put_fid;
+ if (fcall && fcall->id == RWALK)
+ goto clunk_fid;
+ else {
+ v9fs_put_idpool(fid, &v9ses->fidpool);
+ goto free_fcall;
+ }
}
+ kfree(fcall);
/* TODO: do special things for O_EXCL, O_NOFOLLOW, O_SYNC */
/* translate open mode appropriately */
@@ -109,8 +115,7 @@
clunk_fid:
v9fs_t_clunk(v9ses, fid);
-put_fid:
- v9fs_put_idpool(fid, &v9ses->fidpool);
+free_fcall:
kfree(fcall);
return err;
diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 133db36..2cb87ba 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -270,7 +270,10 @@
err = v9fs_t_walk(v9ses, pfid, fid, NULL, &fcall);
if (err < 0) {
PRINT_FCALL_ERROR("clone error", fcall);
- goto put_fid;
+ if (fcall && fcall->id == RWALK)
+ goto clunk_fid;
+ else
+ goto put_fid;
}
kfree(fcall);
@@ -322,6 +325,9 @@
&fcall);
if (err < 0) {
+ if (fcall && fcall->id == RWALK)
+ goto clunk_fid;
+
PRINT_FCALL_ERROR("walk error", fcall);
v9fs_put_idpool(nfid, &v9ses->fidpool);
goto error;
@@ -640,19 +646,26 @@
}
result = v9fs_t_walk(v9ses, dirfidnum, newfid,
- (char *)dentry->d_name.name, NULL);
+ (char *)dentry->d_name.name, &fcall);
+
if (result < 0) {
- v9fs_put_idpool(newfid, &v9ses->fidpool);
+ if (fcall && fcall->id == RWALK)
+ v9fs_t_clunk(v9ses, newfid);
+ else
+ v9fs_put_idpool(newfid, &v9ses->fidpool);
+
if (result == -ENOENT) {
d_add(dentry, NULL);
dprintk(DEBUG_VFS,
"Return negative dentry %p count %d\n",
dentry, atomic_read(&dentry->d_count));
+ kfree(fcall);
return NULL;
}
dprintk(DEBUG_ERROR, "walk error:%d\n", result);
goto FreeFcall;
}
+ kfree(fcall);
result = v9fs_t_stat(v9ses, newfid, &fcall);
if (result < 0) {