| Message ID | 20190410230443.15729-4-atish.patra@wdc.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Miscellaneous kernel command line fixes | expand |
On Wed, Apr 10, 2019 at 04:04:42PM -0700, Atish Patra wrote: > nosmp command line option sets max_cpus to zero. No secondary harts > will boot if this is enabled. But present cpu mask will still point to > all possible masks. > > Fix present cpu mask for nosmp usecase. > > Signed-off-by: Atish Patra <atish.patra@wdc.com> > --- > arch/riscv/kernel/smpboot.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c > index eb533b5c2c8c..a8ad200581aa 100644 > --- a/arch/riscv/kernel/smpboot.c > +++ b/arch/riscv/kernel/smpboot.c > @@ -47,6 +47,17 @@ void __init smp_prepare_boot_cpu(void) > > void __init smp_prepare_cpus(unsigned int max_cpus) > { > + int cpuid; > + > + /* This covers non-smp usecase mandated by "nosmp" option */ > + if (max_cpus == 0) > + return; > + > + for_each_possible_cpu(cpuid) { > + if (cpuid == smp_processor_id()) > + continue; > + set_cpu_present(cpuid, true); > + } Most other architectures seem to use init_cpu_present() here. Otherwise this looks fine to me.
On 4/11/19 12:01 AM, Christoph Hellwig wrote: > On Wed, Apr 10, 2019 at 04:04:42PM -0700, Atish Patra wrote: >> nosmp command line option sets max_cpus to zero. No secondary harts >> will boot if this is enabled. But present cpu mask will still point to >> all possible masks. >> >> Fix present cpu mask for nosmp usecase. >> >> Signed-off-by: Atish Patra <atish.patra@wdc.com> >> --- >> arch/riscv/kernel/smpboot.c | 12 +++++++++++- >> 1 file changed, 11 insertions(+), 1 deletion(-) >> >> diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c >> index eb533b5c2c8c..a8ad200581aa 100644 >> --- a/arch/riscv/kernel/smpboot.c >> +++ b/arch/riscv/kernel/smpboot.c >> @@ -47,6 +47,17 @@ void __init smp_prepare_boot_cpu(void) >> >> void __init smp_prepare_cpus(unsigned int max_cpus) >> { >> + int cpuid; >> + >> + /* This covers non-smp usecase mandated by "nosmp" option */ >> + if (max_cpus == 0) >> + return; >> + >> + for_each_possible_cpu(cpuid) { >> + if (cpuid == smp_processor_id()) >> + continue; >> + set_cpu_present(cpuid, true); >> + } > > Most other architectures seem to use init_cpu_present() here. > I did a quick grep through other archs. Mostly, init_cpu_present is preferred when you update a entire cpumask or cpu 0. We can just use cpu_possible_mask and init_cpu_present together to avoid the loop. It will just set the current boot cpu bit once more. But looking at ARM64 code, we may have to bring back the loop when we have some implementation similar cpu_ops. Regards, Atish > Otherwise this looks fine to me. >
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c index eb533b5c2c8c..a8ad200581aa 100644 --- a/arch/riscv/kernel/smpboot.c +++ b/arch/riscv/kernel/smpboot.c @@ -47,6 +47,17 @@ void __init smp_prepare_boot_cpu(void) void __init smp_prepare_cpus(unsigned int max_cpus) { + int cpuid; + + /* This covers non-smp usecase mandated by "nosmp" option */ + if (max_cpus == 0) + return; + + for_each_possible_cpu(cpuid) { + if (cpuid == smp_processor_id()) + continue; + set_cpu_present(cpuid, true); + } } void __init setup_smp(void) @@ -74,7 +85,6 @@ void __init setup_smp(void) cpuid_to_hartid_map(cpuid) = hart; set_cpu_possible(cpuid, true); - set_cpu_present(cpuid, true); cpuid++; }
nosmp command line option sets max_cpus to zero. No secondary harts will boot if this is enabled. But present cpu mask will still point to all possible masks. Fix present cpu mask for nosmp usecase. Signed-off-by: Atish Patra <atish.patra@wdc.com> --- arch/riscv/kernel/smpboot.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)