Re: [Outreachy kernel] [PATCH 2/5] staging: lustre: ptlrpc: Use list_for_each_entry_safe

From: Julia Lawall
Date: Sun Mar 05 2017 - 12:43:04 EST




On Sun, 5 Mar 2017, simran singhal wrote:

> Doubly linked lists which are iterated using list_empty
> and list_entry macros have been replaced with list_for_each_entry_safe
> macro.
> This makes the iteration simpler and more readable.
>
> This patch replaces the while loop containing list_empty and list_entry
> with list_for_each_entry_safe.
>
> This was done with Coccinelle.
>
> @@
> expression E1;
> identifier I1, I2;
> type T;
> iterator name list_for_each_entry_safe;
> @@
>
> T *I1;
> + T *tmp;
> ...
> - while (list_empty(&E1) == 0)
> + list_for_each_entry_safe (I1, tmp, &E1, I2)
> {
> ...when != T *I1;
> - I1 = list_entry(E1.next, T, I2);
> ...
> }
>
> Signed-off-by: simran singhal <singhalsimran0@xxxxxxxxx>
> ---
> drivers/staging/lustre/lustre/ptlrpc/sec_gc.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/staging/lustre/lustre/ptlrpc/sec_gc.c b/drivers/staging/lustre/lustre/ptlrpc/sec_gc.c
> index 8ffd000..fe1c0af 100644
> --- a/drivers/staging/lustre/lustre/ptlrpc/sec_gc.c
> +++ b/drivers/staging/lustre/lustre/ptlrpc/sec_gc.c
> @@ -98,12 +98,11 @@ void sptlrpc_gc_del_sec(struct ptlrpc_sec *sec)
> static void sec_process_ctx_list(void)
> {
> struct ptlrpc_cli_ctx *ctx;
> + struct ptlrpc_cli_ctx *tmp;

Another improvement would be to define both variables at once:

T *I1
+ , *tmp
;

julia

>
> spin_lock(&sec_gc_ctx_list_lock);
>
> - while (!list_empty(&sec_gc_ctx_list)) {
> - ctx = list_entry(sec_gc_ctx_list.next,
> - struct ptlrpc_cli_ctx, cc_gc_chain);
> + list_for_each_entry_safe(ctx, tmp, &sec_gc_ctx_list, cc_gc_chain) {
> list_del_init(&ctx->cc_gc_chain);
> spin_unlock(&sec_gc_ctx_list_lock);
>
> --
> 2.7.4
>
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