blktrace segfault.

blktrace segfault.

[Aneesh Kumar K.V]

Core was generated by `blktrace -d /dev/hdc'.
Program terminated with signal 11, Segmentation fault.
#0  0xb7e4cdec in ?? ()
(gdb) where
#0  0xb7e4cdec in ?? ()
#1  0xb7dbf000 in ?? ()
#2  0x00021000 in ?? ()
#3  0xb7dee6e8 in ?? ()
#4  0x0804ecf0 in ?? ()
#5  0x00000001 in ?? ()
#6  0x6c616367 in ?? ()
#7  0xbfee3f68 in ?? ()
#8  0xb7f51300 in ?? ()
#9  0x00000168 in ?? ()
#10 0x0804ecf0 in ?? ()
#11 0x00000001 in ?? ()
#12 0xbfee3f88 in ?? ()
#13 0xbfee3f68 in ?? ()
#14 0x080499dc in close_thread (tip=0xb7f1eff4) at blktrace.c:637
Backtrace stopped: frame did not save the PC
(gdb) 


the below diff fix the same.

diff --git a/blktrace.c b/blktrace.c
index 42613a7..4f4fcde 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -1220,6 +1220,7 @@ static int start_devices(void)
 
 	size = ncpus * sizeof(struct thread_information);
 	thread_information = malloc(size * ndevs);
+	memset(thread_information, 0, size*ndevs);
 	if (!thread_information) {
 		fprintf(stderr, "Out of memory, threads (%d)\n", size * ndevs);
 		return 1;

Re: blktrace segfault.

[Jens Axboe]

On Sun, Oct 28 2007, Aneesh Kumar K.V wrote:
> Core was generated by `blktrace -d /dev/hdc'.
> Program terminated with signal 11, Segmentation fault.
> #0  0xb7e4cdec in ?? ()
> (gdb) where
> #0  0xb7e4cdec in ?? ()
> #1  0xb7dbf000 in ?? ()
> #2  0x00021000 in ?? ()
> #3  0xb7dee6e8 in ?? ()
> #4  0x0804ecf0 in ?? ()
> #5  0x00000001 in ?? ()
> #6  0x6c616367 in ?? ()
> #7  0xbfee3f68 in ?? ()
> #8  0xb7f51300 in ?? ()
> #9  0x00000168 in ?? ()
> #10 0x0804ecf0 in ?? ()
> #11 0x00000001 in ?? ()
> #12 0xbfee3f88 in ?? ()
> #13 0xbfee3f68 in ?? ()
> #14 0x080499dc in close_thread (tip=0xb7f1eff4) at blktrace.c:637
> Backtrace stopped: frame did not save the PC
> (gdb) 
> 
> 
> the below diff fix the same.

Thanks, applied!

-- 
Jens Axboe

Re: blktrace segfault.

[Jan Blunck]

On Sun, Oct 28, Aneesh Kumar K.V wrote:

>
> the below diff fix the same.
>
> diff --git a/blktrace.c b/blktrace.c
> index 42613a7..4f4fcde 100644
> --- a/blktrace.c
> +++ b/blktrace.c
> @@ -1220,6 +1220,7 @@ static int start_devices(void)
> 	size = ncpus * sizeof(struct thread_information);
> 	thread_information = malloc(size * ndevs);
> +	memset(thread_information, 0, size*ndevs);
> 	if (!thread_information) {
> 		fprintf(stderr, "Out of memory, threads (%d)\n", size * ndevs);
> 		return 1;

I'm pretty sure you want to make the memset after the NULL-pointer check. If
malloc fails this is segfaulting too.

Re: blktrace segfault.

[Jens Axboe]

On Wed, Nov 14 2007, Jan Blunck wrote:
> On Sun, Oct 28, Aneesh Kumar K.V wrote:
> 
> >
> > the below diff fix the same.
> >
> > diff --git a/blktrace.c b/blktrace.c
> > index 42613a7..4f4fcde 100644
> > --- a/blktrace.c
> > +++ b/blktrace.c
> > @@ -1220,6 +1220,7 @@ static int start_devices(void)
> > 	size = ncpus * sizeof(struct thread_information);
> > 	thread_information = malloc(size * ndevs);
> > +	memset(thread_information, 0, size*ndevs);
> > 	if (!thread_information) {
> > 		fprintf(stderr, "Out of memory, threads (%d)\n", size * ndevs);
> > 		return 1;
> 
> I'm pretty sure you want to make the memset after the NULL-pointer check. If
> malloc fails this is segfaulting too.

Ehm that's indeed a good point, I'll check in a fix for that.

-- 
Jens Axboe

Re: blktrace segfault.

[Christoph Hellwig]

On Wed, Nov 14, 2007 at 10:45:30AM +0100, Jens Axboe wrote:
> > > 	size = ncpus * sizeof(struct thread_information);
> > > 	thread_information = malloc(size * ndevs);
> > > +	memset(thread_information, 0, size*ndevs);
> > > 	if (!thread_information) {
> > > 		fprintf(stderr, "Out of memory, threads (%d)\n", size * ndevs);
> > > 		return 1;
> > 
> > I'm pretty sure you want to make the memset after the NULL-pointer check. If
> > malloc fails this is segfaulting too.
> 
> Ehm that's indeed a good point, I'll check in a fix for that.

Even better just use calloc..

Re: blktrace segfault.

[Jens Axboe]

On Wed, Nov 14 2007, Christoph Hellwig wrote:
> On Wed, Nov 14, 2007 at 10:45:30AM +0100, Jens Axboe wrote:
> > > > 	size = ncpus * sizeof(struct thread_information);
> > > > 	thread_information = malloc(size * ndevs);
> > > > +	memset(thread_information, 0, size*ndevs);
> > > > 	if (!thread_information) {
> > > > 		fprintf(stderr, "Out of memory, threads (%d)\n", size * ndevs);
> > > > 		return 1;
> > > 
> > > I'm pretty sure you want to make the memset after the NULL-pointer check. If
> > > malloc fails this is segfaulting too.
> > 
> > Ehm that's indeed a good point, I'll check in a fix for that.
> 
> Even better just use calloc..

I considered it, but it holds ndevs * ncpus * size, so I thought it was
cleaner to keep it as-is and just move the memset.

-- 
Jens Axboe