| Message ID | E1qtqkk-00AJHA-1u@rmk-PC.armlinux.org.uk (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Headers | show |
| Series | parisc: simplify smp_prepare_boot_cpu() | expand |
On Fri, 20 Oct 2023 15:45:30 +0100 "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk> wrote: > smp_prepare_boot_cpu() reads the cpuid of the first CPU, printing a > message to state which processor booted, and setting it online and > present. > > This cpuid is retrieved from per_cpu(cpu_data, 0).cpuid, which is > initialised in arch/parisc/kernel/processor.c:processor_probe() thusly: > > p = &per_cpu(cpu_data, cpuid); > ... > p->cpuid = cpuid; /* save CPU id */ > > Consequently, the cpuid retrieved seems to be guaranteed to also be > zero, meaning that the message printed in this boils down to: > > pr_info("SMP: bootstrap CPU ID is 0\n"); > > Moreover, since kernel/cpu.c::boot_cpu_init() already sets CPU 0 to > be present and online, there is no need to do this again in > smp_prepare_boot_cpu(). > > Remove this code, and simplify the printk(). > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> LGTM, but trivial comment inline. > --- > arch/parisc/kernel/smp.c | 7 +------ > 1 file changed, 1 insertion(+), 6 deletions(-) > > diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c > index 2019c1f04bd0..989efc8c67a5 100644 > --- a/arch/parisc/kernel/smp.c > +++ b/arch/parisc/kernel/smp.c > @@ -404,13 +404,8 @@ static int smp_boot_one_cpu(int cpuid, struct task_struct *idle) > > void __init smp_prepare_boot_cpu(void) > { > - int bootstrap_processor = per_cpu(cpu_data, 0).cpuid; > - > /* Setup BSP mappings */ Given it's not doing any such thing, I think you should also drop the comment. > - printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor); > - > - set_cpu_online(bootstrap_processor, true); > - set_cpu_present(bootstrap_processor, true); > + pr_info("SMP: bootstrap CPU ID is 0\n"); > } > >
On 10/20/23 16:45, Russell King (Oracle) wrote: > smp_prepare_boot_cpu() reads the cpuid of the first CPU, printing a > message to state which processor booted, and setting it online and > present. > > This cpuid is retrieved from per_cpu(cpu_data, 0).cpuid, which is > initialised in arch/parisc/kernel/processor.c:processor_probe() thusly: > > p = &per_cpu(cpu_data, cpuid); > ... > p->cpuid = cpuid; /* save CPU id */ > > Consequently, the cpuid retrieved seems to be guaranteed to also be > zero, meaning that the message printed in this boils down to: > > pr_info("SMP: bootstrap CPU ID is 0\n"); > > Moreover, since kernel/cpu.c::boot_cpu_init() already sets CPU 0 to > be present and online, there is no need to do this again in > smp_prepare_boot_cpu(). > > Remove this code, and simplify the printk(). > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> applied. Removed the "Setup BSP mappings" comment too, as Jonathan Cameron suggested. Thank you! Helge > --- > arch/parisc/kernel/smp.c | 7 +------ > 1 file changed, 1 insertion(+), 6 deletions(-) > > diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c > index 2019c1f04bd0..989efc8c67a5 100644 > --- a/arch/parisc/kernel/smp.c > +++ b/arch/parisc/kernel/smp.c > @@ -404,13 +404,8 @@ static int smp_boot_one_cpu(int cpuid, struct task_struct *idle) > > void __init smp_prepare_boot_cpu(void) > { > - int bootstrap_processor = per_cpu(cpu_data, 0).cpuid; > - > /* Setup BSP mappings */ > - printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor); > - > - set_cpu_online(bootstrap_processor, true); > - set_cpu_present(bootstrap_processor, true); > + pr_info("SMP: bootstrap CPU ID is 0\n"); > } > >
diff --git a/arch/parisc/kernel/smp.c b/arch/parisc/kernel/smp.c index 2019c1f04bd0..989efc8c67a5 100644 --- a/arch/parisc/kernel/smp.c +++ b/arch/parisc/kernel/smp.c @@ -404,13 +404,8 @@ static int smp_boot_one_cpu(int cpuid, struct task_struct *idle) void __init smp_prepare_boot_cpu(void) { - int bootstrap_processor = per_cpu(cpu_data, 0).cpuid; - /* Setup BSP mappings */ - printk(KERN_INFO "SMP: bootstrap CPU ID is %d\n", bootstrap_processor); - - set_cpu_online(bootstrap_processor, true); - set_cpu_present(bootstrap_processor, true); + pr_info("SMP: bootstrap CPU ID is 0\n"); }
smp_prepare_boot_cpu() reads the cpuid of the first CPU, printing a message to state which processor booted, and setting it online and present. This cpuid is retrieved from per_cpu(cpu_data, 0).cpuid, which is initialised in arch/parisc/kernel/processor.c:processor_probe() thusly: p = &per_cpu(cpu_data, cpuid); ... p->cpuid = cpuid; /* save CPU id */ Consequently, the cpuid retrieved seems to be guaranteed to also be zero, meaning that the message printed in this boils down to: pr_info("SMP: bootstrap CPU ID is 0\n"); Moreover, since kernel/cpu.c::boot_cpu_init() already sets CPU 0 to be present and online, there is no need to do this again in smp_prepare_boot_cpu(). Remove this code, and simplify the printk(). Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> --- arch/parisc/kernel/smp.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)