[PATCH v2 2/8] arm: Remove now superfluous sentinel elem from ctl_table arrays

From: Joel Granados via B4 Relay
Date: Wed Sep 13 2023 - 05:11:48 EST


From: Joel Granados <j.granados@xxxxxxxxxxx>

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@xxxxxxxxxxxxxxxxxxxxxx/)

Removed the sentinel as well as the explicit size from ctl_isa_vars. The
size is redundant as the initialization sets it. Changed
insn_emulation->sysctl from a 2 element array of struct ctl_table to a
simple struct. This has no consequence for the sysctl registration as it
is forwarded as a pointer. Removed sentinel from sve_defatul_vl_table,
sme_default_vl_table, tagged_addr_sysctl_table and
armv8_pmu_sysctl_table.

This removal is safe because register_sysctl_sz and register_sysctl use
the array size in addition to checking for the sentinel.

Signed-off-by: Joel Granados <j.granados@xxxxxxxxxxx>
---
arch/arm/kernel/isa.c | 4 ++--
arch/arm64/kernel/armv8_deprecated.c | 8 +++-----
arch/arm64/kernel/fpsimd.c | 6 ++----
arch/arm64/kernel/process.c | 3 +--
drivers/perf/arm_pmuv3.c | 3 +--
5 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/arch/arm/kernel/isa.c b/arch/arm/kernel/isa.c
index 20218876bef2..0b9c28077092 100644
--- a/arch/arm/kernel/isa.c
+++ b/arch/arm/kernel/isa.c
@@ -16,7 +16,7 @@

static unsigned int isa_membase, isa_portbase, isa_portshift;

-static struct ctl_table ctl_isa_vars[4] = {
+static struct ctl_table ctl_isa_vars[] = {
{
.procname = "membase",
.data = &isa_membase,
@@ -35,7 +35,7 @@ static struct ctl_table ctl_isa_vars[4] = {
.maxlen = sizeof(isa_portshift),
.mode = 0444,
.proc_handler = proc_dointvec,
- }, {}
+ }
};

static struct ctl_table_header *isa_sysctl_header;
diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
index e459cfd33711..dd6ce86d4332 100644
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -52,10 +52,8 @@ struct insn_emulation {
int min;
int max;

- /*
- * sysctl for this emulation + a sentinal entry.
- */
- struct ctl_table sysctl[2];
+ /* sysctl for this emulation */
+ struct ctl_table sysctl;
};

#define ARM_OPCODE_CONDTEST_FAIL 0
@@ -558,7 +556,7 @@ static void __init register_insn_emulation(struct insn_emulation *insn)
update_insn_emulation_mode(insn, INSN_UNDEF);

if (insn->status != INSN_UNAVAILABLE) {
- sysctl = &insn->sysctl[0];
+ sysctl = &insn->sysctl;

sysctl->mode = 0644;
sysctl->maxlen = sizeof(int);
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 91e44ac7150f..db3ad1ba8272 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -588,8 +588,7 @@ static struct ctl_table sve_default_vl_table[] = {
.mode = 0644,
.proc_handler = vec_proc_do_default_vl,
.extra1 = &vl_info[ARM64_VEC_SVE],
- },
- { }
+ }
};

static int __init sve_sysctl_init(void)
@@ -612,8 +611,7 @@ static struct ctl_table sme_default_vl_table[] = {
.mode = 0644,
.proc_handler = vec_proc_do_default_vl,
.extra1 = &vl_info[ARM64_VEC_SME],
- },
- { }
+ }
};

static int __init sme_sysctl_init(void)
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index 0fcc4eb1a7ab..48861cdc3aae 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -723,8 +723,7 @@ static struct ctl_table tagged_addr_sysctl_table[] = {
.proc_handler = proc_dointvec_minmax,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
- },
- { }
+ }
};

static int __init tagged_addr_init(void)
diff --git a/drivers/perf/arm_pmuv3.c b/drivers/perf/arm_pmuv3.c
index e5a2ac4155f6..c4aa6a8d1b05 100644
--- a/drivers/perf/arm_pmuv3.c
+++ b/drivers/perf/arm_pmuv3.c
@@ -1172,8 +1172,7 @@ static struct ctl_table armv8_pmu_sysctl_table[] = {
.proc_handler = armv8pmu_proc_user_access_handler,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
- },
- { }
+ }
};

static void armv8_pmu_register_sysctl_table(void)

--
2.30.2