[BUG?] do_generic_direct_write

From: J.A. Magallon (jamagallon@able.es)
Date: Fri Jun 27 2003 - 18:36:49 EST

On 06.27, Marcelo Tosatti wrote:
>
> Hello,
>
> Here goes -pre2 with a big number of changes, including the new aic7xxx
> driver.
>
> I wont accept any big changes after -pre4: I want 2.4.22 timecycle to be
> short.
>

Correct me if I'm wrong. I found this just by chance:

mm/filemap.c:
ssize_t
do_generic_direct_write(struct file *file,const char *buf,size_t count, loff_t *ppos)
...

    if (!file->f_flags & O_DIRECT)
        BUG();

This fails to trigger the BUG() just when it should. This should be:

    if (!(file->f_flags & O_DIRECT))
        BUG();

To check my C, I tried this:

#include <stdio.h>

#define O_D 2

int main()
{
    int flags;

    flags = O_D +4;
    printf("%d\n",!flags & O_D);
    printf("%d\n",!(flags & O_D));
    flags = 1+4;
    printf("%d\n",!flags & O_D);
    printf("%d\n",!(flags & O_D));

    return 0;
}

Output:

werewolf:~# ./kk
0
0
0
1

So it gives 0 when 'flags' != 0, not regarding if O_D is there or not....

Correct ?

One other job for the Stanford checker... ? 

-- 
J.A. Magallon <jamagallon@able.es>      \                 Software is like sex:
werewolf.able.es                         \           It's better when it's free
Mandrake Linux release 9.2 (Cooker) for i586
Linux 2.4.21-jam1 (gcc 3.3 (Mandrake Linux 9.2 3.3-2mdk))
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This archive was generated by hypermail 2b29 : Mon Jun 30 2003 - 22:00:28 EST