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ALSA: msnd: Optimize / harden DSP and MIDI loops

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commit 20e2b791796bd68816fa115f12be5320de2b8021 upstream.

The ISA msnd drivers have loops fetching the ring-buffer head, tail
and size values inside the loops.  Such codes are inefficient and
fragile.

This patch optimizes it, and also adds the sanity check to avoid the
endless loops.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196131
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196133
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: grygorii tertychnyi <gtertych@cisco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Takashi Iwai 2017-07-06 12:34:40 +02:00 committed by Greg Kroah-Hartman
parent 10863607c2
commit 5568147015
2 changed files with 26 additions and 25 deletions
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28
sound/isa/msnd/msnd_midi.c
View File

@ -120,24 +120,24 @@ void snd_msndmidi_input_read(void *mpuv)
unsigned long flags; unsigned long flags;
struct snd_msndmidi *mpu = mpuv; struct snd_msndmidi *mpu = mpuv;
void *pwMIDQData = mpu->dev->mappedbase + MIDQ_DATA_BUFF; void *pwMIDQData = mpu->dev->mappedbase + MIDQ_DATA_BUFF;
u16 head, tail, size;
spin_lock_irqsave(&mpu->input_lock, flags); spin_lock_irqsave(&mpu->input_lock, flags);
while (readw(mpu->dev->MIDQ + JQS_wTail) != head = readw(mpu->dev->MIDQ + JQS_wHead);
readw(mpu->dev->MIDQ + JQS_wHead)) { tail = readw(mpu->dev->MIDQ + JQS_wTail);
u16 wTmp, val; size = readw(mpu->dev->MIDQ + JQS_wSize);
val = readw(pwMIDQData + 2 * readw(mpu->dev->MIDQ + JQS_wHead)); if (head > size || tail > size)
goto out;
while (head != tail) {
unsigned char val = readw(pwMIDQData + 2 * head);
if (test_bit(MSNDMIDI_MODE_BIT_INPUT_TRIGGER, if (test_bit(MSNDMIDI_MODE_BIT_INPUT_TRIGGER, &mpu->mode))
&mpu->mode)) snd_rawmidi_receive(mpu->substream_input, &val, 1);
snd_rawmidi_receive(mpu->substream_input, if (++head > size)
(unsigned char *)&val, 1); head = 0;
writew(head, mpu->dev->MIDQ + JQS_wHead);
wTmp = readw(mpu->dev->MIDQ + JQS_wHead) + 1;
if (wTmp > readw(mpu->dev->MIDQ + JQS_wSize))
writew(0, mpu->dev->MIDQ + JQS_wHead);
else
writew(wTmp, mpu->dev->MIDQ + JQS_wHead);
} }
out:
spin_unlock_irqrestore(&mpu->input_lock, flags); spin_unlock_irqrestore(&mpu->input_lock, flags);
} }
EXPORT_SYMBOL(snd_msndmidi_input_read); EXPORT_SYMBOL(snd_msndmidi_input_read);

23
sound/isa/msnd/msnd_pinnacle.c
View File

@ -170,23 +170,24 @@ static irqreturn_t snd_msnd_interrupt(int irq, void *dev_id)
{ {
struct snd_msnd *chip = dev_id; struct snd_msnd *chip = dev_id;
void *pwDSPQData = chip->mappedbase + DSPQ_DATA_BUFF; void *pwDSPQData = chip->mappedbase + DSPQ_DATA_BUFF;
u16 head, tail, size;
/* Send ack to DSP */ /* Send ack to DSP */
/* inb(chip->io + HP_RXL); */ /* inb(chip->io + HP_RXL); */
/* Evaluate queued DSP messages */ /* Evaluate queued DSP messages */
while (readw(chip->DSPQ + JQS_wTail) != readw(chip->DSPQ + JQS_wHead)) { head = readw(chip->DSPQ + JQS_wHead);
u16 wTmp; tail = readw(chip->DSPQ + JQS_wTail);
size = readw(chip->DSPQ + JQS_wSize);
snd_msnd_eval_dsp_msg(chip, if (head > size || tail > size)
readw(pwDSPQData + 2 * readw(chip->DSPQ + JQS_wHead))); goto out;
while (head != tail) {
wTmp = readw(chip->DSPQ + JQS_wHead) + 1; snd_msnd_eval_dsp_msg(chip, readw(pwDSPQData + 2 * head));
if (wTmp > readw(chip->DSPQ + JQS_wSize)) if (++head > size)
writew(0, chip->DSPQ + JQS_wHead); head = 0;
else writew(head, chip->DSPQ + JQS_wHead);
writew(wTmp, chip->DSPQ + JQS_wHead);
} }
out:
/* Send ack to DSP */ /* Send ack to DSP */
inb(chip->io + HP_RXL); inb(chip->io + HP_RXL);
return IRQ_HANDLED; return IRQ_HANDLED;