RISC-V: hwprobe: Clarify cpus size parameter

The "count" parameter associated with the 'cpus' parameter of the
hwprobe syscall is the size in bytes of 'cpus'. Naming it 'cpu_count'
may mislead users (it did me) to think it's the number of CPUs that
are or can be represented by 'cpus' instead. This is particularly
easy (IMO) to get wrong since 'cpus' is documented to be defined by
CPU_SET(3) and CPU_SET(3) also documents a CPU_COUNT() (the number
of CPUs in set) macro. CPU_SET(3) refers to the size of cpu sets
with 'setsize'. Adopt 'cpusetsize' for the hwprobe parameter and
specifically state it is in bytes in Documentation/riscv/hwprobe.rst
to clarify.

Reviewed-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20231122164700.127954-7-ajones@ventanamicro.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

2 files changed, 12 insertions, 12 deletions

diff --git a/arch/riscv/kernel/sys_riscv.c b/arch/riscv/kernel/sys_riscv.c
index c712037dbe10..5e4deb1308b8 100644
--- a/arch/riscv/kernel/sys_riscv.c
+++ b/arch/riscv/kernel/sys_riscv.c
@@ -246,7 +246,7 @@ static void hwprobe_one_pair(struct riscv_hwprobe *pair,
 }
 
 static int do_riscv_hwprobe(struct riscv_hwprobe __user *pairs,
-			    size_t pair_count, size_t cpu_count,
+			    size_t pair_count, size_t cpusetsize,
 			    unsigned long __user *cpus_user,
 			    unsigned int flags)
 {
@@ -264,13 +264,13 @@ static int do_riscv_hwprobe(struct riscv_hwprobe __user *pairs,
 	 * 0 as a shortcut to all online CPUs.
 	 */
 	cpumask_clear(&cpus);
-	if (!cpu_count && !cpus_user) {
+	if (!cpusetsize && !cpus_user) {
 		cpumask_copy(&cpus, cpu_online_mask);
 	} else {
-		if (cpu_count > cpumask_size())
-			cpu_count = cpumask_size();
+		if (cpusetsize > cpumask_size())
+			cpusetsize = cpumask_size();
 
-		ret = copy_from_user(&cpus, cpus_user, cpu_count);
+		ret = copy_from_user(&cpus, cpus_user, cpusetsize);
 		if (ret)
 			return -EFAULT;
 
@@ -347,10 +347,10 @@ arch_initcall_sync(init_hwprobe_vdso_data);
 #endif /* CONFIG_MMU */
 
 SYSCALL_DEFINE5(riscv_hwprobe, struct riscv_hwprobe __user *, pairs,
-		size_t, pair_count, size_t, cpu_count, unsigned long __user *,
+		size_t, pair_count, size_t, cpusetsize, unsigned long __user *,
 		cpus, unsigned int, flags)
 {
-	return do_riscv_hwprobe(pairs, pair_count, cpu_count,
+	return do_riscv_hwprobe(pairs, pair_count, cpusetsize,
 				cpus, flags);
 }
 
diff --git a/arch/riscv/kernel/vdso/hwprobe.c b/arch/riscv/kernel/vdso/hwprobe.c
index cadf725ef798..026b7645c5ab 100644
--- a/arch/riscv/kernel/vdso/hwprobe.c
+++ b/arch/riscv/kernel/vdso/hwprobe.c
@@ -8,21 +8,21 @@
 #include <vdso/helpers.h>
 
 extern int riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
-			 size_t cpu_count, unsigned long *cpus,
+			 size_t cpusetsize, unsigned long *cpus,
 			 unsigned int flags);
 
 /* Add a prototype to avoid -Wmissing-prototypes warning. */
 int __vdso_riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
-			 size_t cpu_count, unsigned long *cpus,
+			 size_t cpusetsize, unsigned long *cpus,
 			 unsigned int flags);
 
 int __vdso_riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
-			 size_t cpu_count, unsigned long *cpus,
+			 size_t cpusetsize, unsigned long *cpus,
 			 unsigned int flags)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();
 	const struct arch_vdso_data *avd = &vd->arch_data;
-	bool all_cpus = !cpu_count && !cpus;
+	bool all_cpus = !cpusetsize && !cpus;
 	struct riscv_hwprobe *p = pairs;
 	struct riscv_hwprobe *end = pairs + pair_count;
 
@@ -33,7 +33,7 @@ int __vdso_riscv_hwprobe(struct riscv_hwprobe *pairs, size_t pair_count,
 	 * masks.
 	 */
 	if ((flags != 0) || (!all_cpus && !avd->homogeneous_cpus))
-		return riscv_hwprobe(pairs, pair_count, cpu_count, cpus, flags);
+		return riscv_hwprobe(pairs, pair_count, cpusetsize, cpus, flags);
 
 	/* This is something we can handle, fill out the pairs. */
 	while (p < end) {