Messages in this thread | | | From | "Zengtao (B)" <> | Subject | RE: [PATCH v2] cpu-topology: Skip the exist but not possible cpu nodes | Date | Tue, 14 Jan 2020 01:42:25 +0000 |
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> -----Original Message----- > From: Sudeep Holla [mailto:sudeep.holla@arm.com] > Sent: Monday, January 13, 2020 8:21 PM > To: Zengtao (B) > Cc: Linuxarm; Greg Kroah-Hartman; Rafael J. Wysocki; Sudeep Holla; > linux-kernel@vger.kernel.org > Subject: Re: [PATCH v2] cpu-topology: Skip the exist but not possible cpu > nodes > > On Mon, Jan 13, 2020 at 12:06:11PM +0000, Zengtao (B) wrote: > > > -----Original Message----- > > > From: Sudeep Holla [mailto:sudeep.holla@arm.com] > > > Sent: Monday, January 13, 2020 6:19 PM > > > To: Zengtao (B) > > > Cc: Linuxarm; Greg Kroah-Hartman; Rafael J. Wysocki; Sudeep Holla; > > > linux-kernel@vger.kernel.org > > > Subject: Re: [PATCH v2] cpu-topology: Skip the exist but not possible > cpu > > > nodes > > > > > > On Sat, Jan 11, 2020 at 02:53:40PM +0800, Zeng Tao wrote: > > > > When CONFIG_NR_CPUS is smaller than the cpu nodes defined in > the > > > device > > > > tree, all the cpu nodes parsing will fail. > > > > And this is not reasonable for a legal device tree configs. > > > > In this patch, skip such cpu nodes rather than return an error. > > > > With CONFIG_NR_CPUS = 128 and cpus nodes num in device tree > is > > > 130, > > > > The following warning messages will be print during boot: > > > > CPU node for /cpus/cpu@128 exist but the possible cpu range > > > is :0-127 > > > > CPU node for /cpus/cpu@129 exist but the possible cpu range > > > is :0-127 > > > > CPU node for /cpus/cpu@130 exist but the possible cpu range > > > is :0-127 > > > > > > > > Signed-off-by: Zeng Tao <prime.zeng@hisilicon.com> > > > > --- > > > > Changelog: > > > > v1->v2: > > > > -Remove redundant -ENODEV assignment in get_cpu_for_node > > > > -Add comment to describe the get_cpu_for_node return values > > > > -Add skip process for cpu threads > > > > -Update the commit log with more detail > > > > --- > > > > drivers/base/arch_topology.c | 37 > > > +++++++++++++++++++++++++++++-------- > > > > 1 file changed, 29 insertions(+), 8 deletions(-) > > > > > > > > diff --git a/drivers/base/arch_topology.c > > > b/drivers/base/arch_topology.c > > > > index 5fe44b3..01f0e21 100644 > > > > --- a/drivers/base/arch_topology.c > > > > +++ b/drivers/base/arch_topology.c > > > > @@ -248,22 +248,44 @@ core_initcall(free_raw_capacity); > > > > #endif > > > > > > > > #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV) > > > > +/* > > > > + * This function returns the logic cpu number of the node. > > > > + * There are totally three kinds of return values: > > > > + * (1) logic cpu number which is > 0. > > > > + * (2) -ENDEV when the node is valid one which can be found in > the > > > device tree > > > > + * but there is no possible cpu nodes to match, when the > > > CONFIG_NR_CPUS is > > > > + * smaller than cpus node numbers in device tree, this will > happen. > > > It's > > > > + * suggested to just ignore this case. > > > > > > s/ENDEV/ENODEV/ > > Good catch, thanks. > > > > > > > > Also as I mentioned earlier, I prefer not to add any extra logic here > > > other than the above comment to make it explicit. This triggers > > > unnecessary > > > warnings when someone boots with limited CPUs for valid reasons. > > > > > > > So , what 's your suggestion here? Just keep the comments but remove > > the warning message print? > > Yes for all the "found" logic. I am fine to update the existing err >
Find, I will take it. . > > > > > > > + * (3) -EINVAL when other errors occur. > > > > + */ > > > > static int __init get_cpu_for_node(struct device_node *node) > > > > { > > > > - struct device_node *cpu_node; > > > > + struct device_node *cpu_node, *t; > > > > int cpu; > > > > + bool found = false; > > > > > > > > cpu_node = of_parse_phandle(node, "cpu", 0); > > > > if (!cpu_node) > > > > - return -1; > > > > + return -EINVAL; > > > > + > > > > + for_each_of_cpu_node(t) > > > > + if (t == cpu_node) { > > > > + found = true; > > > > + break; > > > > + } > > > > + > > > > + if (!found) { > > > > + pr_crit("Unable to find CPU node for %pOF\n", > cpu_node); > > > > + return -EINVAL; > > > > + } > > Drop all the above change.
Could you help to explain here? I understand there are two abnormal cases: 1. The cpu node exist in the device tree, but not a possible cpu. This case can be caught by of_cpu_node_to_id's return value. 2. The cpu node does not exist. This case can be caught by above logic. Or do you think of_parse_phandle's return value is enough?
> > > > > > > > > cpu = of_cpu_node_to_id(cpu_node); > > > > if (cpu >= 0) > > > > topology_parse_cpu_capacity(cpu_node, cpu); > > You can add here: else if (cpu == -ENODEV) > pr_info(...whatever you have below..) > > Other things as is. Warning may be too harsh if one is running with > reduced number of CPUs. > > > > > else > > > > - pr_crit("Unable to find CPU node for %pOF\n", > cpu_node); > > > > + pr_warn("CPU node for %pOF exist but the possible cpu > range > > > is :%*pbl\n", > > > > + cpu_node, cpumask_pr_args(cpu_possible_mask)); > > > > > > > > - of_node_put(cpu_node); > > > > > > Why is this dropped ? > > > > It's unnecessary here since no one get the node ref. > > > > Please read the description of of_parse_phandle. If you find other > issues with existing code, address it in separate patch and don't mix > with the issue in $subject. > ^_^, got it , will remove, Thanks
Regards Zengtao
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