ALSA: hdsp: Break infinite MIDI input flush loop

The current MIDI input flush on HDSP and HDSPM drivers relies on the
hardware reporting the right value.  If the hardware doesn't give the
proper value but returns -1, it may be stuck at an infinite loop.

Add a counter and break if the loop is unexpectedly too long.

Link: https://patch.msgid.link/20240808091513.31380-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/rme9652/hdsp.c b/sound/pci/rme9652/hdsp.c
index e7d1b43..713ca26 100644 (file)
--- a/sound/pci/rme9652/hdsp.c
+++ b/sound/pci/rme9652/hdsp.c
@@ -1298,8 +1298,10 @@ static int snd_hdsp_midi_output_possible (struct hdsp *hdsp, int id)
 
 static void snd_hdsp_flush_midi_input (struct hdsp *hdsp, int id)
 {
-       while (snd_hdsp_midi_input_available (hdsp, id))
-               snd_hdsp_midi_read_byte (hdsp, id);
+       int count = 256;
+
+       while (snd_hdsp_midi_input_available(hdsp, id) && --count)
+               snd_hdsp_midi_read_byte(hdsp, id);
 }
 
 static int snd_hdsp_midi_output_write (struct hdsp_midi *hmidi)

diff --git a/sound/pci/rme9652/hdspm.c b/sound/pci/rme9652/hdspm.c
index 56d335f..c3f930a 100644 (file)
--- a/sound/pci/rme9652/hdspm.c
+++ b/sound/pci/rme9652/hdspm.c
@@ -1838,8 +1838,10 @@ static inline int snd_hdspm_midi_output_possible (struct hdspm *hdspm, int id)
 
 static void snd_hdspm_flush_midi_input(struct hdspm *hdspm, int id)
 {
-       while (snd_hdspm_midi_input_available (hdspm, id))
-               snd_hdspm_midi_read_byte (hdspm, id);
+       int count = 256;
+
+       while (snd_hdspm_midi_input_available(hdspm, id) && --count)
+               snd_hdspm_midi_read_byte(hdspm, id);
 }
 
 static int snd_hdspm_midi_output_write (struct hdspm_midi *hmidi)