Re: [PATCH 10/12] x86, mce: cleanup mce_read

Borislav Petkov
2011-05-27T06:38:12Z

On Fri, May 27, 2011 at 01:11:34PM +0900, Hidetoshi Seto wrote:
> Use temporary local entry to make code simple.
> No change in logic.
>
> Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
> ---
> arch/x86/kernel/cpu/mcheck/mce.c | 19 +++++++++----------
> 1 files changed, 9 insertions(+), 10 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
> index 9fe9e6e..4ba4040 100644
> --- a/arch/x86/kernel/cpu/mcheck/mce.c
> +++ b/arch/x86/kernel/cpu/mcheck/mce.c
> @@ -1533,18 +1533,17 @@ static ssize_t mce_read(struct file *filp, char __user *ubuf, size_t usize,
> do {
> for (i = prev; i < next; i++) {
> unsigned long start = jiffies;
> + struct mce *entry = &mcelog.entry[i];

Just go ahead and call it m:

struct mce *m = ...

we know it's an mce struct.

>
> - while (!mcelog.entry[i].finished) {
> + while (!entry->finished) {
> if (time_after_eq(jiffies, start + 2)) {
> - memset(mcelog.entry + i, 0,
> - sizeof(struct mce));
> + memset(entry, 0, sizeof(struct mce));

..and thus you can do

memset(m, 0, sizeof(*m));

and that's too short for some taste but since the definition is close
enough, we should still be readable.

> goto timeout;
> }
> cpu_relax();
> }
> smp_rmb();
> - err |= copy_to_user(buf, mcelog.entry + i,
> - sizeof(struct mce));
> + err |= copy_to_user(buf, entry, sizeof(struct mce));
> buf += sizeof(struct mce);
> timeout:
> ;
> @@ -1565,13 +1564,13 @@ timeout:
> on_each_cpu(collect_tscs, cpu_tsc, 1);
>
> for (i = next; i < MCE_LOG_LEN; i++) {
> - if (mcelog.entry[i].finished &&
> - mcelog.entry[i].tsc < cpu_tsc[mcelog.entry[i].cpu]) {
> - err |= copy_to_user(buf, mcelog.entry+i,
> - sizeof(struct mce));
> + struct mce *entry = &mcelog.entry[i];
> +
> + if (entry->finished && entry->tsc < cpu_tsc[entry->cpu]) {
> + err |= copy_to_user(buf, entry, sizeof(struct mce));
> smp_rmb();
> buf += sizeof(struct mce);
> - memset(&mcelog.entry[i], 0, sizeof(struct mce));
> + memset(entry, 0, sizeof(struct mce));
> }
> }
>
> --
> 1.7.1
>
>
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--
Regards/Gruss,
Boris.