From 41e5a6ac80c600e1f8bda0a4871f0b797e097d78 Mon Sep 17 00:00:00 2001 From: Latchesar Ionkov Date: Mon, 15 May 2006 09:44:21 -0700 Subject: [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 Cc: Eric Van Hensbergen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/9p/mux.c | 222 +++++++++++++++++++++++++++++++++++------------------------- 1 file changed, 131 insertions(+), 91 deletions(-) (limited to 'fs/9p/mux.c') diff --git a/fs/9p/mux.c b/fs/9p/mux.c index 3e5b124a7212..f4407eb276c7 100644 --- a/fs/9p/mux.c +++ b/fs/9p/mux.c @@ -50,15 +50,23 @@ enum { 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_poll_task { 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 @@ again: 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 @@ static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req) 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 @@ static void v9fs_read_work(void *a) 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 @@ static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m, return ERR_PTR(-ENOMEM); v9fs_set_tag(tc, n); - if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) { char buf[150]; @@ -754,12 +752,14 @@ static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m, 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 @@ static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m, 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); + + if (req->cb) + (*req->cb) (req, req->cba); + else + kfree(req->rcall); + + wake_up(&m->equeue); + } - v9fs_mux_put_tag(m, tag); - kfree(tc); - kfree(rc); + 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 @@ int 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 @@ v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc, 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 @@ void v9fs_mux_cancel(struct v9fs_mux_data *m, int err) 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 @@ void v9fs_mux_cancel(struct v9fs_mux_data *m, int err) 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); -- cgit v1.2.2