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SubjectRe: 2.2.18: Thread problem with smbfs
Date
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Hi,

Urban Widmark wrote:

> I don't really know how signal delivery works within the kernel, but
> smb_trans2_request tries to disable some signals. That does not work
> (completely?) so either it needs fixing or the -512 errno needs to be
> handled.
>
> Why so bad in gdb? perhaps it causes more signals.
> Why does one thread end up in D state? don't know.
>
>
> > Kernel 2.2.18, smbfs as a module. I can provide more info if necessary.
>
> A small testprogram that causes this would be nice. The -512 is easy to
> reproduce but I haven't seen the 'D' before.
>
> If someone is interested the relevant code is fs/smbfs/sock.c
> (smb_trans2_request, ..., _recvfrom)

Here is a test program to reproduce this. Don't worry about
missing error checks and so on, it's just a quick hack.
Create the required files file1..file5 on a SMB share and edit
the #define accordingly. File sizes of 1-2 MB should suffice.
Then run the program. It should copy the files to the current
directory. Then run it under gdb. It should hang until you kill
gdb.

I tested only with a NT 4 server (sp 5 or 6).

Regards,
hjb

#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

/* Size of the blocks we read from a file. */
static const int ChunkSize = 8192;

/* Path on the mounted SMB share from which we copy files */
#define SourcePath "/mnt/net/test"

struct CopyThreadInfo
{
char* src;
char* dst;
};

/* returns 1 on success */
int CopyFile(char* src, char* dst)
{
char buffer[ChunkSize];
int f, g;
ssize_t nRet;
int nError;

if ((f = open(src, O_RDONLY)) < 0)
return 0;

g = open(dst, O_WRONLY | O_CREAT | O_TRUNC, 0666);
if (g < 0)
{
close(f);
return 0;
}

do
{
nRet = read(f, buffer, sizeof(buffer));
if (nRet < 0 && errno == EINTR)
nRet = 0;
if (nRet < 0)
{
return 0;
}
if (nRet > 0)
nRet = write(g, buffer, nRet);
} while (nRet > 0);

close(g);
close(f);

if (nRet < 0)
return 0;

return 1;
}

void* Copy(struct CopyThreadInfo *info)
{
CopyFile(info->src, info->dst);
return NULL;
}

void Fetch(char* name)
{
char src[4096];
char dst[4096];

pthread_attr_t attr;
pthread_t pid;
struct CopyThreadInfo* pCopy = (struct CopyThreadInfo *) malloc(sizeof(struct CopyThreadInfo));

strcpy(src, SourcePath);
strcat(src, name);
strcpy(dst, name);

pCopy->src = strdup(src);
pCopy->dst = strdup(dst);

pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
pthread_create(&pid, &attr, Copy, pCopy);
}

int main()
{
Fetch("file1");
Fetch("file2");
Fetch("file3");
Fetch("file4");
Fetch("file5");
while(1)
;
return 0;
}


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