Re: [PATCH] kexec: Delete an unnecessary comparison

From: Joe Perches
Date: Fri Aug 14 2020 - 02:07:28 EST


On Thu, 2020-08-13 at 20:45 +0800, Youling Tang wrote:
> Regardless of whether the ret value is zero or non-zero, the trajectory
> of the program execution is the same, so there is no need to compare.
>
> Signed-off-by: Youling Tang <tangyouling@xxxxxxxxxxx>
> ---
> kernel/kexec_file.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 78c0837..3ad0ae2 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -800,8 +800,6 @@ static int kexec_calculate_store_digests(struct kimage *image)
>
> ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
> digest, SHA256_DIGEST_SIZE, 0);
> - if (ret)
> - goto out_free_digest;
> }
>
> out_free_digest:

If you really want to change the function, then
you could change a couple of breaks to gotos,
remove multiple unnecessary tests, and unindent
a block of code too.

---
kernel/kexec_file.c | 30 ++++++++++++------------------
1 file changed, 12 insertions(+), 18 deletions(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index ca40bef75a61..34a025e85887 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -763,7 +763,7 @@ static int kexec_calculate_store_digests(struct kimage *image)
ret = crypto_shash_update(desc, ksegment->kbuf,
ksegment->bufsz);
if (ret)
- break;
+ goto out_free_digest;

/*
* Assume rest of the buffer is filled with zero and
@@ -777,32 +777,26 @@ static int kexec_calculate_store_digests(struct kimage *image)
bytes = zero_buf_sz;
ret = crypto_shash_update(desc, zero_buf, bytes);
if (ret)
- break;
+ goto out_free_digest;
nullsz -= bytes;
}

- if (ret)
- break;
-
sha_regions[j].start = ksegment->mem;
sha_regions[j].len = ksegment->memsz;
j++;
}

- if (!ret) {
- ret = crypto_shash_final(desc, digest);
- if (ret)
- goto out_free_digest;
- ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
- sha_regions, sha_region_sz, 0);
- if (ret)
- goto out_free_digest;
+ ret = crypto_shash_final(desc, digest);
+ if (ret)
+ goto out_free_digest;

- ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
- digest, SHA256_DIGEST_SIZE, 0);
- if (ret)
- goto out_free_digest;
- }
+ ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
+ sha_regions, sha_region_sz, 0);
+ if (ret)
+ goto out_free_digest;
+
+ ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
+ digest, SHA256_DIGEST_SIZE, 0);

out_free_digest:
kfree(digest);