Re: [HPDD-discuss] [PATCH] staging: lustre: fix sparse warning on LPROC_SEQ_FOPS macros
Andreas,
On Sat, Dec 06, 2014 at 05:05:14PM +0000, Dilger, Andreas wrote:
On 2014/12/05, 3:41 PM, "Tristan Lelong"
<tristan(a)lelong.xyz> wrote:
Sorry, but I don't see where you get 80 from? fh_name is declared as a
"const char *", and initialized in the declaration of fld_hash[]. I'd
thought to reply that sizeof(fh_name) would even be better than a #define,
but sizeof(const char *) doesn't actually make sense.
You are right, I got confused with the names trying to follow the declaration of the
variable.
The longest declared fh_name is 4 characters, but I'm not sure of
an easy
way to determine this at compile time. I guess one option is to change
the declaration of struct lu_fld_hash to use "const char fh_name[4];" and
then use sizeof(fh_name), but I don't know if that is better than just
declaring a small buffer (8 chars) for this usage. IMHO that is small
enough to fit on the stack, since it is at the top of a very short
callchain (userspace->sys_write->vfs_write->fld_proc_hash_seq_write())
that just saves the value so the chance of stack overflow is basically nil.
I can implement any of those 2 options. If somebody as a strong preference, let me know,
otherwise I'll follow Andreas idea and will redo the patch with a stack name variable
of size 8.
Cheers, Andreas
--
Andreas Dilger
Lustre Software Architect
Intel High Performance Data Division
Thanks for your comment and help.