channel.c: Fix usage of CHECK_BLOCKING()

The CHECK_BLOCKING() macro is used to indicate if a channel's handling
thread is about to do a blocking operation (poll, read, or write) of
media.  A few operations such as ast_queue_frame(), soft hangup, and
masquerades use the indication to wake up the blocked thread to reevaluate
what is going on.

ASTERISK-27625

Change-Id: I4dfc33e01e60627d962efa29d0a4244cf151a84d

diff --git a/include/asterisk/channel.h b/include/asterisk/channel.h
index 0fc236af4bafc30e6b6dc6def3f6e832c830e1ef..8c171b6f1b8e4feb03501b4f4f412f1234c4b370 100644 (file)
--- a/include/asterisk/channel.h
+++ b/include/asterisk/channel.h
@@ -2649,15 +2649,30 @@ static inline enum ast_t38_state ast_channel_get_t38_state(struct ast_channel *c
        return state;
 }
 
-#define CHECK_BLOCKING(c) do {          \
-       if (ast_test_flag(ast_channel_flags(c), AST_FLAG_BLOCKING)) {\
-               ast_debug(1, "Thread %p is blocking '%s', already blocked by thread %p in procedure %s\n", \
-                       (void *) pthread_self(), ast_channel_name(c), (void *) ast_channel_blocker(c), ast_channel_blockproc(c)); \
-       } else { \
+/*!
+ * \brief Set the blocking indication on the channel.
+ *
+ * \details
+ * Indicate that the thread handling the channel is about to do a blocking
+ * operation to wait for media on the channel.  (poll, read, or write)
+ *
+ * Masquerading and ast_queue_frame() use this indication to wake up the thread.
+ *
+ * \pre The channel needs to be locked
+ */
+#define CHECK_BLOCKING(c) \
+       do { \
+               if (ast_test_flag(ast_channel_flags(c), AST_FLAG_BLOCKING)) { \
+                       /* This should not happen as there should only be one thread handling a channel's media at a time. */ \
+                       ast_log(LOG_DEBUG, "Thread %p is blocking '%s', already blocked by thread %p in procedure %s\n", \
+                               (void *) pthread_self(), ast_channel_name(c), \
+                               (void *) ast_channel_blocker(c), ast_channel_blockproc(c)); \
+                       ast_assert(0); \
+               } \
                ast_channel_blocker_set((c), pthread_self()); \
                ast_channel_blockproc_set((c), __PRETTY_FUNCTION__); \
                ast_set_flag(ast_channel_flags(c), AST_FLAG_BLOCKING); \
-       } } while (0)
+       } while (0)
 
 ast_group_t ast_get_group(const char *s);
 

diff --git a/main/channel.c b/main/channel.c
index 27a959a4b9bc1683ead70fbe1cba521d131416ad..2a72aeed21b69368310e47ae2bbb2ad7950d946d 100644 (file)
--- a/main/channel.c
+++ b/main/channel.c
@@ -3266,11 +3266,11 @@ static struct ast_channel *ast_waitfor_nandfds_simple(struct ast_channel *chan,
                }
        }
 
-       ast_channel_unlock(chan);
-
        /* Time to make this channel block... */
        CHECK_BLOCKING(chan);
 
+       ast_channel_unlock(chan);
+
        if (*ms > 0) {
                start = ast_tvnow();
        }
@@ -3279,7 +3279,9 @@ static struct ast_channel *ast_waitfor_nandfds_simple(struct ast_channel *chan,
        res = epoll_wait(ast_channel_epfd(chan), ev, 1, rms);
 
        /* Stop blocking */
+       ast_channel_lock(chan);
        ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
+       ast_channel_unlock(chan);
 
        /* Simulate a timeout if we were interrupted */
        if (res < 0) {
@@ -3305,12 +3307,14 @@ static struct ast_channel *ast_waitfor_nandfds_simple(struct ast_channel *chan,
 
        /* See what events are pending */
        aed = ev[0].data.ptr;
+       ast_channel_lock(chan);
        ast_channel_fdno_set(chan, aed->which);
        if (ev[0].events & EPOLLPRI) {
                ast_set_flag(ast_channel_flags(chan), AST_FLAG_EXCEPTION);
        } else {
                ast_clear_flag(ast_channel_flags(chan), AST_FLAG_EXCEPTION);
        }
+       ast_channel_unlock(chan);
 
        if (*ms > 0) {
                *ms -= ast_tvdiff_ms(ast_tvnow(), start);
@@ -3346,8 +3350,8 @@ static struct ast_channel *ast_waitfor_nandfds_complex(struct ast_channel **c, i
                                whentohangup = diff;
                        }
                }
-               ast_channel_unlock(c[i]);
                CHECK_BLOCKING(c[i]);
+               ast_channel_unlock(c[i]);
        }
 
        rms = *ms;
@@ -3365,7 +3369,9 @@ static struct ast_channel *ast_waitfor_nandfds_complex(struct ast_channel **c, i
        res = epoll_wait(ast_channel_epfd(c[0]), ev, 25, rms);
 
        for (i = 0; i < n; i++) {
+               ast_channel_lock(c[i]);
                ast_clear_flag(ast_channel_flags(c[i]), AST_FLAG_BLOCKING);
+               ast_channel_unlock(c[i]);
        }
 
        if (res < 0) {
@@ -3400,12 +3406,14 @@ static struct ast_channel *ast_waitfor_nandfds_complex(struct ast_channel **c, i
                }
 
                winner = aed->chan;
+               ast_channel_lock(winner);
                if (ev[i].events & EPOLLPRI) {
                        ast_set_flag(ast_channel_flags(winner), AST_FLAG_EXCEPTION);
                } else {
                        ast_clear_flag(ast_channel_flags(winner), AST_FLAG_EXCEPTION);
                }
                ast_channel_fdno_set(winner, aed->which);
+               ast_channel_unlock(winner);
        }
 
        if (*ms > 0) {
@@ -5220,11 +5228,9 @@ int ast_write(struct ast_channel *chan, struct ast_frame *fr)
                                /* There is a generator running while we're in the middle of a digit.
                                 * It's probably inband DTMF, so go ahead and pass it so it can
                                 * stop the generator */
-                               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
                                ast_channel_unlock(chan);
                                res = ast_senddigit_end(chan, fr->subclass.integer, fr->len);
                                ast_channel_lock(chan);
-                               CHECK_BLOCKING(chan);
                        } else if (fr->frametype == AST_FRAME_CONTROL
                                && fr->subclass.integer == AST_CONTROL_UNHOLD) {
                                /*
@@ -5242,7 +5248,6 @@ int ast_write(struct ast_channel *chan, struct ast_frame *fr)
        /* High bit prints debugging */
        if (ast_channel_fout(chan) & DEBUGCHAN_FLAG)
                ast_frame_dump(ast_channel_name(chan), fr, ">>");
-       CHECK_BLOCKING(chan);
        switch (fr->frametype) {
        case AST_FRAME_CONTROL:
                indicate_data_internal(chan, fr->subclass.integer, fr->data.ptr, fr->datalen);
@@ -5256,11 +5261,9 @@ int ast_write(struct ast_channel *chan, struct ast_frame *fr)
                                f = fr;
                }
                send_dtmf_begin_event(chan, DTMF_SENT, fr->subclass.integer);
-               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
                ast_channel_unlock(chan);
                res = ast_senddigit_begin(chan, fr->subclass.integer);
                ast_channel_lock(chan);
-               CHECK_BLOCKING(chan);
                break;
        case AST_FRAME_DTMF_END:
                if (ast_channel_audiohooks(chan)) {
@@ -5272,13 +5275,12 @@ int ast_write(struct ast_channel *chan, struct ast_frame *fr)
                        }
                }
                send_dtmf_end_event(chan, DTMF_SENT, fr->subclass.integer, fr->len);
-               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
                ast_channel_unlock(chan);
                res = ast_senddigit_end(chan, fr->subclass.integer, fr->len);
                ast_channel_lock(chan);
-               CHECK_BLOCKING(chan);
                break;
        case AST_FRAME_TEXT:
+               CHECK_BLOCKING(chan);
                if (ast_format_cmp(fr->subclass.format, ast_format_t140) == AST_FORMAT_CMP_EQUAL) {
                        res = (ast_channel_tech(chan)->write_text == NULL) ? 0 :
                                ast_channel_tech(chan)->write_text(chan, fr);
@@ -5286,19 +5288,26 @@ int ast_write(struct ast_channel *chan, struct ast_frame *fr)
                        res = (ast_channel_tech(chan)->send_text == NULL) ? 0 :
                                ast_channel_tech(chan)->send_text(chan, (char *) fr->data.ptr);
                }
+               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
                break;
        case AST_FRAME_HTML:
+               CHECK_BLOCKING(chan);
                res = (ast_channel_tech(chan)->send_html == NULL) ? 0 :
                        ast_channel_tech(chan)->send_html(chan, fr->subclass.integer, (char *) fr->data.ptr, fr->datalen);
+               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
                break;
        case AST_FRAME_VIDEO:
                /* XXX Handle translation of video codecs one day XXX */
+               CHECK_BLOCKING(chan);
                res = (ast_channel_tech(chan)->write_video == NULL) ? 0 :
                        ast_channel_tech(chan)->write_video(chan, fr);
+               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
                break;
        case AST_FRAME_MODEM:
+               CHECK_BLOCKING(chan);
                res = (ast_channel_tech(chan)->write == NULL) ? 0 :
                        ast_channel_tech(chan)->write(chan, fr);
+               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
                break;
        case AST_FRAME_VOICE:
                if (ast_channel_tech(chan)->write == NULL)
@@ -5459,6 +5468,7 @@ int ast_write(struct ast_channel *chan, struct ast_frame *fr)
                /* the translator on chan->writetrans may have returned multiple frames
                   from the single frame we passed in; if so, feed each one of them to the
                   channel, freeing each one after it has been written */
+               CHECK_BLOCKING(chan);
                if ((f != fr) && AST_LIST_NEXT(f, frame_list)) {
                        struct ast_frame *cur, *next = NULL;
                        unsigned int skip = 0;
@@ -5487,6 +5497,7 @@ int ast_write(struct ast_channel *chan, struct ast_frame *fr)
                } else {
                        res = ast_channel_tech(chan)->write(chan, f);
                }
+               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
                break;
        case AST_FRAME_NULL:
        case AST_FRAME_IAX:
@@ -5497,13 +5508,14 @@ int ast_write(struct ast_channel *chan, struct ast_frame *fr)
                /* At this point, fr is the incoming frame and f is NULL.  Channels do
                 * not expect to get NULL as a frame pointer and will segfault.  Hence,
                 * we output the original frame passed in. */
+               CHECK_BLOCKING(chan);
                res = ast_channel_tech(chan)->write(chan, fr);
+               ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
                break;
        }
 
        if (f && f != fr)
                ast_frfree(f);
-       ast_clear_flag(ast_channel_flags(chan), AST_FLAG_BLOCKING);
 
        /* Consider a write failure to force a soft hangup */
        if (res < 0) {