| Message ID | 20230630105938.1377262-1-suagrfillet@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [V2] riscv: Add BUG_ON() for no cpu nodes in devicetree | expand |
On Fri, Jun 30, 2023 at 06:59:38PM +0800, Song Shuai wrote: > When only the ACPI tables are passed to kernel, the tiny devictree created > by EFI Stub doesn't provide cpu nodes. > > While if append the "acpi=off" to kernel cmdline to disable ACPI for kernel > the BUG_ON() in of_parse_and_init_cpus() indicates there's no boot cpu > found in the devicetree, not there're no cpu nodes in the devicetree. > > Add BUG_ON() in the first place of of_parse_and_init_cpus() to make it clear. > > Signed-off-by: Song Shuai <suagrfillet@gmail.com> I'm still not really convinced that this is needed - not finding the boot CPU is a strong a hint as any that your DT is completely broken. Especially if you intentionally go out of your way to disable ACPI on a system that requires it to boot. I'll leave it up to Palmer or whoever to determine whether this is a valuable change. Code change itself much improved though, thanks - I'd give an R-b/A-b other than that I question whether there's any value in adding another BUG_ON(). You could've kept the part of the comment that explained what the error meant though, but that's not a big deal. Thanks, Conor. > --- > Changes since V1: > https://lore.kernel.org/linux-riscv/20230629105839.1160895-1-suagrfillet@gmail.com/ > - revise the commit-msg and move the BUG_ON into of_parse_and_init_cpus() as Conor suggests > > --- > arch/riscv/kernel/smpboot.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c > index 6ca2b5309aab..04d33afbdf55 100644 > --- a/arch/riscv/kernel/smpboot.c > +++ b/arch/riscv/kernel/smpboot.c > @@ -147,6 +147,8 @@ static void __init of_parse_and_init_cpus(void) > int cpuid = 1; > int rc; > > + BUG_ON(!of_get_next_cpu_node(NULL)); > + > cpu_set_ops(0); > > for_each_of_cpu_node(dn) { > -- > 2.20.1 > > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
On Fri, 30 Jun 2023 11:39:24 PDT (-0700), Conor Dooley wrote: > On Fri, Jun 30, 2023 at 06:59:38PM +0800, Song Shuai wrote: >> When only the ACPI tables are passed to kernel, the tiny devictree created >> by EFI Stub doesn't provide cpu nodes. >> >> While if append the "acpi=off" to kernel cmdline to disable ACPI for kernel >> the BUG_ON() in of_parse_and_init_cpus() indicates there's no boot cpu >> found in the devicetree, not there're no cpu nodes in the devicetree. >> >> Add BUG_ON() in the first place of of_parse_and_init_cpus() to make it clear. >> >> Signed-off-by: Song Shuai <suagrfillet@gmail.com> > > I'm still not really convinced that this is needed - not finding the > boot CPU is a strong a hint as any that your DT is completely broken. > Especially if you intentionally go out of your way to disable ACPI on a > system that requires it to boot. > > I'll leave it up to Palmer or whoever to determine whether this is a > valuable change. Code change itself much improved though, thanks - I'd > give an R-b/A-b other than that I question whether there's any value in > adding another BUG_ON(). You could've kept the part of the comment that > explained what the error meant though, but that's not a big deal. IIUC this is just reduntant: if the BUG_ON triggers then there's no CPUs, so we'll end up with no iterations of the loop and thus no found CPU and thus a BUG_ON. The only difference is the SBI probing, but that's just poking SBI to turn off spinwait. So I think we already crash sufficiently on systems with an empty DT. Sorry if I'm missing something, though? > Thanks, > Conor. > >> --- >> Changes since V1: >> https://lore.kernel.org/linux-riscv/20230629105839.1160895-1-suagrfillet@gmail.com/ >> - revise the commit-msg and move the BUG_ON into of_parse_and_init_cpus() as Conor suggests >> >> --- >> arch/riscv/kernel/smpboot.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c >> index 6ca2b5309aab..04d33afbdf55 100644 >> --- a/arch/riscv/kernel/smpboot.c >> +++ b/arch/riscv/kernel/smpboot.c >> @@ -147,6 +147,8 @@ static void __init of_parse_and_init_cpus(void) >> int cpuid = 1; >> int rc; >> >> + BUG_ON(!of_get_next_cpu_node(NULL)); >> + >> cpu_set_ops(0); >> >> for_each_of_cpu_node(dn) { >> -- >> 2.20.1 >> >> >> _______________________________________________ >> linux-riscv mailing list >> linux-riscv@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-riscv
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c index 6ca2b5309aab..04d33afbdf55 100644 --- a/arch/riscv/kernel/smpboot.c +++ b/arch/riscv/kernel/smpboot.c @@ -147,6 +147,8 @@ static void __init of_parse_and_init_cpus(void) int cpuid = 1; int rc; + BUG_ON(!of_get_next_cpu_node(NULL)); + cpu_set_ops(0); for_each_of_cpu_node(dn) {
When only the ACPI tables are passed to kernel, the tiny devictree created by EFI Stub doesn't provide cpu nodes. While if append the "acpi=off" to kernel cmdline to disable ACPI for kernel the BUG_ON() in of_parse_and_init_cpus() indicates there's no boot cpu found in the devicetree, not there're no cpu nodes in the devicetree. Add BUG_ON() in the first place of of_parse_and_init_cpus() to make it clear. Signed-off-by: Song Shuai <suagrfillet@gmail.com> --- Changes since V1: https://lore.kernel.org/linux-riscv/20230629105839.1160895-1-suagrfillet@gmail.com/ - revise the commit-msg and move the BUG_ON into of_parse_and_init_cpus() as Conor suggests --- arch/riscv/kernel/smpboot.c | 2 ++ 1 file changed, 2 insertions(+)