a7y18lte-ubports/android_kernel_samsung_universal7885
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

ARM: SMP: use a timing out completion for cpu hotplug

Browse Source 
Rather than open-coding the jiffy-based wait, and polling for the
secondary CPU to come online, use a completion instead.  This
removes the need to poll, instead we will be notified when the
secondary CPU has initialized.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Russell King 2012-01-18 15:59:45 +00:00
parent 94e5a85b3b
commit 149c24151e
1 changed files with 6 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
arch/arm/kernel/smp.c
View File

@ -58,6 +58,8 @@ enum ipi_msg_type {
IPI_CPU_STOP, IPI_CPU_STOP,
}; };
static DECLARE_COMPLETION(cpu_running);
int __cpuinit __cpu_up(unsigned int cpu) int __cpuinit __cpu_up(unsigned int cpu)
{ {
struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu); struct cpuinfo_arm *ci = &per_cpu(cpu_data, cpu);
@ -98,20 +100,12 @@ int __cpuinit __cpu_up(unsigned int cpu)
*/ */
ret = boot_secondary(cpu, idle); ret = boot_secondary(cpu, idle);
if (ret == 0) { if (ret == 0) {
unsigned long timeout;
/* /*
* CPU was successfully started, wait for it * CPU was successfully started, wait for it
* to come online or time out. * to come online or time out.
*/ */
timeout = jiffies + HZ; wait_for_completion_timeout(&cpu_running,
while (time_before(jiffies, timeout)) { msecs_to_jiffies(1000));
if (cpu_online(cpu))
break;
udelay(10);
barrier();
}
if (!cpu_online(cpu)) { if (!cpu_online(cpu)) {
pr_crit("CPU%u: failed to come online\n", cpu); pr_crit("CPU%u: failed to come online\n", cpu);
@ -300,9 +294,10 @@ asmlinkage void __cpuinit secondary_start_kernel(void)
/* /*
* OK, now it's safe to let the boot CPU continue. Wait for * OK, now it's safe to let the boot CPU continue. Wait for
* the CPU migration code to notice that the CPU is online * the CPU migration code to notice that the CPU is online
* before we continue. * before we continue - which happens after __cpu_up returns.
*/ */
set_cpu_online(cpu, true); set_cpu_online(cpu, true);
complete(&cpu_running);
/* /*
* Setup the percpu timer for this CPU. * Setup the percpu timer for this CPU.