linux-kernel - [PATCH] kexec: Avoid calculating array size twice

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Message-Id: <20230525-kexec-array_size-v1-1-8b4bf4f7500a@kernel.org>
Date:   Thu, 25 May 2023 16:26:25 +0200
From:   Simon Horman <horms@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Eric Biederman <ebiederm@...ssion.com>,
        Baoquan He <bhe@...hat.com>,
        "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] kexec: Avoid calculating array size twice

Avoid calculating array size twice in kexec_purgatory_setup_sechdrs().
Once using array_size(), and once open-coded.

Flagged by Coccinelle:

  .../kexec_file.c:881:8-25: WARNING: array_size is already used (line 877) to compute the same size

No functional change intended.
Compile tested only.

Signed-off-by: Simon Horman <horms@...nel.org>
---
 kernel/kexec_file.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
index f989f5f1933b..3f5677679744 100644
--- a/kernel/kexec_file.c
+++ b/kernel/kexec_file.c
@@ -867,6 +867,7 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
 {
 	unsigned long bss_addr;
 	unsigned long offset;
+	size_t sechdrs_size;
 	Elf_Shdr *sechdrs;
 	int i;
 
@@ -874,11 +875,11 @@ static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
 	 * The section headers in kexec_purgatory are read-only. In order to
 	 * have them modifiable make a temporary copy.
 	 */
-	sechdrs = vzalloc(array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum));
+	sechdrs_size = array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum);
+	sechdrs = vzalloc(sechdrs_size);
 	if (!sechdrs)
 		return -ENOMEM;
-	memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff,
-	       pi->ehdr->e_shnum * sizeof(Elf_Shdr));
+	memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff, sechdrs_size);
 	pi->sechdrs = sechdrs;
 
 	offset = 0;