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Subject[PATCH] Re: Segmentation fault in i810_audio.c:__i810_update_lvi
On Tue, May 11, 2004 at 12:27:28AM -0700, Andrew Morton wrote:
> Gary Wong <gtw@cs.bu.edu> wrote:
> > I believe that one of two fixes should be applied: either the
> > SNDCTL_DSP_SETTRIGGER ioctl handling should not enable the
> > PCM_ENABLE_{IN,OUT}PUT bits unless file->f_mode is compatible,
> > or i810_release() should ignore the PCM_ENABLE_* bits without
> > the corresponding FMODE_*.
>
> The first option sounds more appropriate but I wonder if it could break
> existing applications? Probably not, if it oopses.

I agree; I had a look at a few other drivers at random (audio, esssolo1,
trident) and they all silently ignore inappropriate PCM_ENABLE_* bits.

> Let's try option #1, please.

OK, a patch is attached. It seems to fix the problem on a 2.6.3 system
with Herbert Xu's patches from Jeff Garzik applied.

break-i810.c is a small test case which hopefully demonstrates the
problem.

Cheers,
Gary.
--
Gary Wong gtw@cs.bu.edu http://cs-people.bu.edu/gtw/
--- i810_audio.c.herbert 2004-05-11 12:36:05.674715334 -0400
+++ i810_audio.c 2004-05-11 12:41:50.101624990 -0400
@@ -2186,6 +2186,10 @@
#if defined(DEBUG) || defined(DEBUG_MMAP)
printk("SNDCTL_DSP_SETTRIGGER 0x%x\n", val);
#endif
+ if (!(file->f_mode & FMODE_READ ))
+ val &= ~PCM_ENABLE_INPUT;
+ if (!(file->f_mode & FMODE_WRITE ))
+ val &= ~PCM_ENABLE_OUTPUT;
if((file->f_mode & FMODE_READ) && !(val & PCM_ENABLE_INPUT) && dmabuf->enable == ADC_RUNNING) {
stop_adc(state);
}
@@ -2193,7 +2197,7 @@
stop_dac(state);
}
dmabuf->trigger = val;
- if((file->f_mode & FMODE_WRITE) && (val & PCM_ENABLE_OUTPUT) && !(dmabuf->enable & DAC_RUNNING)) {
+ if((val & PCM_ENABLE_OUTPUT) && !(dmabuf->enable & DAC_RUNNING)) {
if (!dmabuf->write_channel) {
dmabuf->ready = 0;
dmabuf->write_channel = state->card->alloc_pcm_channel(state->card);
@@ -2214,7 +2218,7 @@
i810_update_lvi(state, 0);
start_dac(state);
}
- if((file->f_mode & FMODE_READ) && (val & PCM_ENABLE_INPUT) && !(dmabuf->enable & ADC_RUNNING)) {
+ if((val & PCM_ENABLE_INPUT) && !(dmabuf->enable & ADC_RUNNING)) {
if (!dmabuf->read_channel) {
dmabuf->ready = 0;
dmabuf->read_channel = state->card->alloc_rec_pcm_channel(state->card);#include <fcntl.h>
#include <sys/ioctl.h>
#include <sys/soundcard.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

extern int main( void ) {
#define DSP "/dev/dsp"

int f = open( DSP, O_RDONLY );
int i, n;
fd_set fds;

if( f < 0 ) {
perror( DSP );
return EXIT_FAILURE;
}
n = 0;
if( ioctl( f, SNDCTL_DSP_SETTRIGGER, &n ) < 0 ) {
perror( "SNDCTL_DSP_SETTRIGGER" );
return EXIT_FAILURE;
}
n = PCM_ENABLE_INPUT | PCM_ENABLE_OUTPUT;
if( ioctl( f, SNDCTL_DSP_SETTRIGGER, &n ) < 0 ) {
perror( "SNDCTL_DSP_SETTRIGGER" );
return EXIT_FAILURE;
}
for( i = 0; i < 10; i++ ) {
char a[ 1024 ];
FD_ZERO( &fds );
FD_SET( f, &fds );

if( select( f + 1, &fds, NULL, NULL, NULL ) < 0 )
perror( "select" );
if( read( f, a, 1024 ) < 0 )
perror( "read" );
}
close( f );

return EXIT_SUCCESS;
}
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