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Subject[PATCH v3 3/3] reboot: refactor and comment the cpu selection code
Date
From: Matteo Croce <mcroce@microsoft.com>

Small improvements to the code, without changing the way it works:
- use a local variable, to avoid a small time lapse where reboot_cpu
can have an invalid value
- comment the code which is not easy to understand at a glance
- merge two identical code blocks into one
- replace pointer arithmetics with equivalent array syntax

Signed-off-by: Matteo Croce <mcroce@microsoft.com>
---
kernel/reboot.c | 30 +++++++++++++++++-------------
1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/kernel/reboot.c b/kernel/reboot.c
index af6f23d8bea1..dd483bde932b 100644
--- a/kernel/reboot.c
+++ b/kernel/reboot.c
@@ -551,20 +551,24 @@ static int __init reboot_setup(char *str)
break;

case 's':
- if (isdigit(*(str+1)))
- reboot_cpu = simple_strtoul(str+1, NULL, 0);
- else if (str[1] == 'm' && str[2] == 'p' &&
- isdigit(*(str+3)))
- reboot_cpu = simple_strtoul(str+3, NULL, 0);
- else
+ /*
+ * reboot_cpu is s[mp]#### with #### being the processor
+ * to be used for rebooting. Skip 's' or 'smp' prefix.
+ */
+ str += str[1] == 'm' && str[2] == 'p' ? 3 : 1;
+
+ if (isdigit(str[0])) {
+ int cpu = simple_strtoul(str, NULL, 0);
+
+ if (cpu >= num_possible_cpus()) {
+ pr_err("Ignoring the CPU number in reboot= option. "
+ "CPU %d exceeds possible cpu number %d\n",
+ cpu, num_possible_cpus());
+ break;
+ }
+ reboot_cpu = cpu;
+ } else
*mode = REBOOT_SOFT;
- if (reboot_cpu >= num_possible_cpus()) {
- pr_err("Ignoring the CPU number in reboot= option. "
- "CPU %d exceeds possible cpu number %d\n",
- reboot_cpu, num_possible_cpus());
- reboot_cpu = 0;
- break;
- }
break;

case 'g':
--
2.28.0
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