Hi Heather,
On Tue, 2023-10-10 at 15:42 +0200, Mark Wielaard wrote:
> From: Heather McIntyre <h...@rice.edu>
>
> * libelf/elf_cntl.c (elf_cntl): Move rwlock_wrlock, rwlock_unlock,
> inside case switch statements.
>
> Signed-off-by: Heather S. McIntyre <h...@rice.edu>
> Signed-off-by: Mark Wielaard <m...@klomp.org>
> ---
> libelf/elf_cntl.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/libelf/elf_cntl.c b/libelf/elf_cntl.c
> index 04aa9132..64087c7d 100644
> --- a/libelf/elf_cntl.c
> +++ b/libelf/elf_cntl.c
> @@ -48,13 +48,16 @@ elf_cntl (Elf *elf, Elf_Cmd cmd)
> return -1;
> }
>
> - rwlock_wrlock (elf->lock);
> +
>
> switch (cmd)
> {
> case ELF_C_FDREAD:
> + rwlock_rdlock (elf->lock);
> + int addr_isnull = elf->map_address == NULL;
> + rwlock_unlock(elf->lock);
> /* If not all of the file is in the memory read it now. */
> - if (elf->map_address == NULL && __libelf_readall (elf) == NULL)
> + if (addr_isnull && __libelf_readall (elf) == NULL)
> {
> /* We were not able to read everything. */
> result = -1;
Can't we just rely on if (__libelf_readall (elf) == NULL)?
__libelf_readall already does locking and will return non-NULL if elf-
>map_address is already set. So it looks like the extra check (and
locking) to check addr_isnull is redundant and just make the code more
complex.
> @@ -64,7 +67,9 @@ elf_cntl (Elf *elf, Elf_Cmd cmd)
>
> case ELF_C_FDDONE:
> /* Mark the file descriptor as not usable. */
> + rwlock_wrlock (elf->lock);
> elf->fildes = -1;
> + rwlock_unlock (elf->lock);
> break;
>
> default:
This looks correct. All other accesses to elf->fildes seem to be done
under the elf->lock too.
> @@ -73,7 +78,5 @@ elf_cntl (Elf *elf, Elf_Cmd cmd)
> break;
> }
>
> - rwlock_unlock (elf->lock);
> -
> return result;
> }
