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BUG/MEDIUM: mux-h2: don't needlessly wake up the demux on short frames

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In some situations, if too short a frame header is received, we may leave
h2_process_demux() waking up the task again without checking that we were
already subscribed.

In order to avoid this once for all, let's introduce an h2_restart_reading()
function which performs the control and calls the task up. This way we won't
needlessly wake the task up if it's already waiting for I/O.

Must be backported to 1.9.
This commit is contained in:
Willy Tarreau 2018-12-21 16:09:41 +01:00
parent e98ce25b61
commit 47b515a462
1 changed files with 20 additions and 16 deletions
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36
src/mux_h2.c
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@ -284,6 +284,17 @@ static inline int h2_recv_allowed(const struct h2c *h2c)
return 0;
}
/* restarts reading on the connection if it was not enabled */
static inline void h2c_restart_reading(const struct h2c *h2c)
{
if (!h2_recv_allowed(h2c))
return;
if (h2c->wait_event.events & SUB_RETRY_RECV)
return;
tasklet_wakeup(h2c->wait_event.task);
}
/* returns true if the connection has too many conn_streams attached */
static inline int h2_has_too_many_cs(const struct h2c *h2c)
{
@ -302,8 +313,7 @@ static int h2_buf_available(void *target)
if ((h2c->flags & H2_CF_DEM_DALLOC) && b_alloc_margin(&h2c->dbuf, 0)) {
h2c->flags &= ~H2_CF_DEM_DALLOC;
if (h2_recv_allowed(h2c))
tasklet_wakeup(h2c->wait_event.task);
h2c_restart_reading(h2c);
return 1;
}
@ -312,8 +322,7 @@ static int h2_buf_available(void *target)
if (h2c->flags & H2_CF_DEM_MROOM) {
h2c->flags &= ~H2_CF_DEM_MROOM;
if (h2_recv_allowed(h2c))
tasklet_wakeup(h2c->wait_event.task);
h2c_restart_reading(h2c);
}
return 1;
}
@ -322,8 +331,7 @@ static int h2_buf_available(void *target)
(h2s = h2c_st_by_id(h2c, h2c->dsi)) && h2s->cs &&
b_alloc_margin(&h2s->rxbuf, 0)) {
h2c->flags &= ~H2_CF_DEM_SALLOC;
if (h2_recv_allowed(h2c))
tasklet_wakeup(h2c->wait_event.task);
h2c_restart_reading(h2c);
return 1;
}
@ -467,7 +475,7 @@ static int h2_init(struct connection *conn, struct proxy *prx, struct session *s
conn->ctx = h2c;
/* prepare to read something */
tasklet_wakeup(h2c->wait_event.task);
h2c_restart_reading(h2c);
return 0;
fail_stream:
hpack_dht_free(h2c->ddht);
@ -2375,8 +2383,7 @@ static void h2_process_demux(struct h2c *h2c)
h2s_notify_recv(h2s);
}
if (h2_recv_allowed(h2c))
tasklet_wakeup(h2c->wait_event.task);
h2c_restart_reading(h2c);
}
/* process Tx frames from streams to be multiplexed. Returns > 0 if it reached
@ -2848,8 +2855,7 @@ static void h2_detach(struct conn_stream *cs)
if (h2c->flags & H2_CF_DEM_TOOMANY &&
!h2_has_too_many_cs(h2c)) {
h2c->flags &= ~H2_CF_DEM_TOOMANY;
if (h2_recv_allowed(h2c))
tasklet_wakeup(h2c->wait_event.task);
h2c_restart_reading(h2c);
}
/* this stream may be blocked waiting for some data to leave (possibly
@ -2867,7 +2873,7 @@ static void h2_detach(struct conn_stream *cs)
*/
h2c->flags &= ~H2_CF_DEM_BLOCK_ANY;
h2c->flags &= ~H2_CF_MUX_BLOCK_ANY;
tasklet_wakeup(h2c->wait_event.task);
h2c_restart_reading(h2c);
}
h2s_destroy(h2s);
@ -4663,10 +4669,8 @@ static size_t h2_rcv_buf(struct conn_stream *cs, struct buffer *buf, size_t coun
if (ret && h2c->dsi == h2s->id) {
/* demux is blocking on this stream's buffer */
h2c->flags &= ~H2_CF_DEM_SFULL;
if (b_data(&h2c->dbuf) || !(h2c->wait_event.events & SUB_RETRY_RECV)) {
if (h2_recv_allowed(h2c))
tasklet_wakeup(h2c->wait_event.task);
}
if (b_data(&h2c->dbuf) || !(h2c->wait_event.events & SUB_RETRY_RECV))
h2c_restart_reading(h2c);
}
end:
return ret;