On 19/6/6 04:49, Gustavo A. R. Silva wrote:
> One of the more common cases of allocation size calculations is finding
> the size of a structure that has a zero-sized array at the end, along
> with memory for some number of elements for that array. For example:
>
> struct dlm_migratable_lockres
> {
> i ...
> struct dlm_migratable_lock ml[0]; // 16 bytes each, begins at byte
> 112
> };
>
> Make use of the struct_size() helper instead of an open-coded version
> in order to avoid any potential type mistakes.
>
> So, replace the following form:
>
> sizeof(struct dlm_migratable_lockres) + (mres->num_locks * sizeof(struct
> dlm_migratable_lock))
>
> with:
>
> struct_size(mres, ml, mres->num_locks)
>
> Notice that, in this case, variable sz is not necessary, hence it
> is removed.
>
> This code was detected with the help of Coccinelle.
>
> Signed-off-by: Gustavo A. R. Silva <[email protected]>
Reviewed-by: Joseph Qi <[email protected]>
> ---
> fs/ocfs2/dlm/dlmrecovery.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
> index e22d6a115220..064ce5bbc3f6 100644
> --- a/fs/ocfs2/dlm/dlmrecovery.c
> +++ b/fs/ocfs2/dlm/dlmrecovery.c
> @@ -1109,7 +1109,7 @@ static int dlm_send_mig_lockres_msg(struct dlm_ctxt
> *dlm,
> {
> u64 mig_cookie = be64_to_cpu(mres->mig_cookie);
> int mres_total_locks = be32_to_cpu(mres->total_locks);
> - int sz, ret = 0, status = 0;
> + int ret = 0, status = 0;
> u8 orig_flags = mres->flags,
> orig_master = mres->master;
>
> @@ -1117,9 +1117,6 @@ static int dlm_send_mig_lockres_msg(struct dlm_ctxt
> *dlm,
> if (!mres->num_locks)
> return 0;
>
> - sz = sizeof(struct dlm_migratable_lockres) +
> - (mres->num_locks * sizeof(struct dlm_migratable_lock));
> -
> /* add an all-done flag if we reached the last lock */
> orig_flags = mres->flags;
> BUG_ON(total_locks > mres_total_locks);
> @@ -1133,7 +1130,8 @@ static int dlm_send_mig_lockres_msg(struct dlm_ctxt
> *dlm,
>
> /* send it */
> ret = o2net_send_message(DLM_MIG_LOCKRES_MSG, dlm->key, mres,
> - sz, send_to, &status);
> + struct_size(mres, ml, mres->num_locks),
> + send_to, &status);
> if (ret < 0) {
> /* XXX: negative status is not handled.
> * this will end up killing this node. */
>
