[PATCH 4.19 082/134] staging: speakup_soft: Fix alternate speech with other synths

[Greg Kroah-Hartman]

4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Samuel Thibault <samuel.thiba...@ens-lyon.org>

commit 45ac7b31bc6c4af885cc5b5d6c534c15bcbe7643 upstream.

When switching from speakup_soft to another synth, speakup_soft would
keep calling synth_buffer_getc() from softsynthx_read.

Let's thus make synth.c export the knowledge of the current synth, so
that speakup_soft can determine whether it should be running.

speakup_soft also needs to set itself alive, otherwise the switch would
let it remain silent.

Signed-off-by: Samuel Thibault <samuel.thiba...@ens-lyon.org>
Cc: stable <sta...@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/staging/speakup/speakup_soft.c |   16 +++++++++++-----
 drivers/staging/speakup/spk_priv.h     |    1 +
 drivers/staging/speakup/synth.c        |    6 ++++++
 3 files changed, 18 insertions(+), 5 deletions(-)

--- a/drivers/staging/speakup/speakup_soft.c
+++ b/drivers/staging/speakup/speakup_soft.c
@@ -208,12 +208,15 @@ static ssize_t softsynthx_read(struct fi
                return -EINVAL;
 
        spin_lock_irqsave(&speakup_info.spinlock, flags);
+       synth_soft.alive = 1;
        while (1) {
                prepare_to_wait(&speakup_event, &wait, TASK_INTERRUPTIBLE);
-               if (!unicode)
-                       synth_buffer_skip_nonlatin1();
-               if (!synth_buffer_empty() || speakup_info.flushing)
-                       break;
+               if (synth_current() == &synth_soft) {
+                       if (!unicode)
+                               synth_buffer_skip_nonlatin1();
+                       if (!synth_buffer_empty() || speakup_info.flushing)
+                               break;
+               }
                spin_unlock_irqrestore(&speakup_info.spinlock, flags);
                if (fp->f_flags & O_NONBLOCK) {
                        finish_wait(&speakup_event, &wait);
@@ -233,6 +236,8 @@ static ssize_t softsynthx_read(struct fi
 
        /* Keep 3 bytes available for a 16bit UTF-8-encoded character */
        while (chars_sent <= count - bytes_per_ch) {
+               if (synth_current() != &synth_soft)
+                       break;
                if (speakup_info.flushing) {
                        speakup_info.flushing = 0;
                        ch = '\x18';
@@ -329,7 +334,8 @@ static __poll_t softsynth_poll(struct fi
        poll_wait(fp, &speakup_event, wait);
 
        spin_lock_irqsave(&speakup_info.spinlock, flags);
-       if (!synth_buffer_empty() || speakup_info.flushing)
+       if (synth_current() == &synth_soft &&
+           (!synth_buffer_empty() || speakup_info.flushing))
                ret = EPOLLIN | EPOLLRDNORM;
        spin_unlock_irqrestore(&speakup_info.spinlock, flags);
        return ret;
--- a/drivers/staging/speakup/spk_priv.h
+++ b/drivers/staging/speakup/spk_priv.h
@@ -72,6 +72,7 @@ int synth_request_region(unsigned long s
 int synth_release_region(unsigned long start, unsigned long n);
 int synth_add(struct spk_synth *in_synth);
 void synth_remove(struct spk_synth *in_synth);
+struct spk_synth *synth_current(void);
 
 extern struct speakup_info_t speakup_info;
 
--- a/drivers/staging/speakup/synth.c
+++ b/drivers/staging/speakup/synth.c
@@ -481,4 +481,10 @@ void synth_remove(struct spk_synth *in_s
 }
 EXPORT_SYMBOL_GPL(synth_remove);
 
+struct spk_synth *synth_current(void)
+{
+       return synth;
+}
+EXPORT_SYMBOL_GPL(synth_current);
+
 short spk_punc_masks[] = { 0, SOME, MOST, PUNC, PUNC | B_SYM };