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SubjectRe: [PATCH] x86/cpuid: Use macro instead of number in cpuid_read()
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On March 5, 2020 1:33:18 AM PST, Yu Chen <chen.yu@easystack.cn> wrote:
>Make and use macro CHUNK_SIZE, instead of numeric value 16 in
>cpuid_read().
>
>Signed-off-by: Yu Chen <chen.yu@easystack.cn>
>---
> arch/x86/kernel/cpuid.c | 13 ++++++++-----
> 1 file changed, 8 insertions(+), 5 deletions(-)
>
>diff --git a/arch/x86/kernel/cpuid.c b/arch/x86/kernel/cpuid.c
>index 3492aa36b..f7d7e0ef7 100644
>--- a/arch/x86/kernel/cpuid.c
>+++ b/arch/x86/kernel/cpuid.c
>@@ -48,6 +48,9 @@ struct cpuid_regs_done {
> struct completion done;
> };
>
>+/* cpuid must be read in chunks of 16 bytes */
>+#define CHUNK_SIZE 16
>+
> static void cpuid_smp_cpuid(void *cmd_block)
> {
> struct cpuid_regs_done *cmd = cmd_block;
>@@ -69,11 +72,11 @@ static ssize_t cpuid_read(struct file *file, char
>__user *buf,
> ssize_t bytes = 0;
> int err = 0;
>
>- if (count % 16)
>+ if (count % CHUNK_SIZE)
> return -EINVAL; /* Invalid chunk size */
>
> init_completion(&cmd.done);
>- for (; count; count -= 16) {
>+ for (; count; count -= CHUNK_SIZE) {
> call_single_data_t csd = {
> .func = cpuid_smp_cpuid,
> .info = &cmd,
>@@ -86,12 +89,12 @@ static ssize_t cpuid_read(struct file *file, char
>__user *buf,
> if (err)
> break;
> wait_for_completion(&cmd.done);
>- if (copy_to_user(tmp, &cmd.regs, 16)) {
>+ if (copy_to_user(tmp, &cmd.regs, CHUNK_SIZE)) {
> err = -EFAULT;
> break;
> }
>- tmp += 16;
>- bytes += 16;
>+ tmp += CHUNK_SIZE;
>+ bytes += CHUNK_SIZE;
> *ppos = ++pos;
> reinit_completion(&cmd.done);
> }

It would make more sense to define a structure and add it to a uapi header.
--
Sent from my Android device with K-9 Mail. Please excuse my brevity.

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