Hi Ted,
On Mon, Jun 3, 2013 at 6:33 PM, Theodore Ts'o <tytso@xxxxxxx> wrote:
> On Mon, Jun 03, 2013 at 01:00:15PM +0300, Ruslan Bilovol wrote:
>> The memset() doesn't perform any NULL-pointer checking
>> before dereferencing passed pointer so this should be
>> checked before calling it.
>
> I can see that __getblk() can return NULL if there is a memory
> allocation failure (and is defined to do so), so checking to make sure
> bh is not NULL is a good thing to do.
>
> Have you actually seen a case where bh is non-NULL, but bh->b_data is
> NULL? If not, it might be better to do something like this:
Yes, this is exactly the situation I observe (bh is non-NULL, but
bh->b_data is NULL)
>
>> bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
> if (!bh)
> return NULL;
> BUG_ON(!bh->b_data);
Is it so critical that we need to stop the kernel here?
Can we recover from this state gracefully?
Maybe something like this may be better:
bh = __getblk(journal->j_dev, blocknr, journal->j_blocksize);
if (!bh)
return NULL;
if(!bh->b_data) {
WARN_ON(1);
return NULL;
}
Regards,
Ruslan
>
> - Ted
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--
Best regards,
Ruslan Bilvol
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