2024-02-13 21:17:07

by Thomas Gleixner

[permalink] [raw]
Subject: [patch 10/30] x86/cpu/topology: Simplify APIC registration

From: Thomas Gleixner <[email protected]>

Having the same check whether the number of assigned CPUs has reached the
nr_cpu_ids limit twice in the same code path is pointless. Repeating the
information that CPUs are ignored over and over is also pointless noise.

Remove the redundant check and reduce the noise by using a pr_warn_once().

Signed-off-by: Thomas Gleixner <[email protected]>


---
arch/x86/kernel/cpu/topology.c | 23 +++--------------------
1 file changed, 3 insertions(+), 20 deletions(-)
---

--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -107,14 +107,6 @@ static int allocate_logical_cpuid(u32 ap
if (cpu >= 0)
return cpu;

- /* Allocate a new cpuid. */
- if (nr_logical_cpuids >= nr_cpu_ids) {
- WARN_ONCE(1, "APIC: NR_CPUS/possible_cpus limit of %u reached. "
- "Processor %d/0x%x and the rest are ignored.\n",
- nr_cpu_ids, nr_logical_cpuids, apic_id);
- return -EINVAL;
- }
-
cpuid_to_apicid[nr_logical_cpuids] = apic_id;
return nr_logical_cpuids++;
}
@@ -135,7 +127,7 @@ static void cpu_update_apic(int cpu, u32

static int generic_processor_info(int apicid)
{
- int cpu, max = nr_cpu_ids;
+ int cpu;

/* The boot CPU must be set before MADT/MPTABLE parsing happens */
if (cpuid_to_apicid[0] == BAD_APICID)
@@ -155,21 +147,12 @@ static int generic_processor_info(int ap
}

if (num_processors >= nr_cpu_ids) {
- int thiscpu = max + disabled_cpus;
-
- pr_warn("APIC: NR_CPUS/possible_cpus limit of %i reached. "
- "Processor %d/0x%x ignored.\n", max, thiscpu, apicid);
-
+ pr_warn_once("APIC: CPU limit of %d reached. Ignoring further CPUs\n", nr_cpu_ids);
disabled_cpus++;
- return -EINVAL;
+ return -ENOSPC;
}

cpu = allocate_logical_cpuid(apicid);
- if (cpu < 0) {
- disabled_cpus++;
- return -EINVAL;
- }
-
cpu_update_apic(cpu, apicid);
return cpu;
}





Subject: [tip: x86/apic] x86/cpu/topology: Simplify APIC registration

The following commit has been merged into the x86/apic branch of tip:

Commit-ID: 4c4c6f38704ab0e3f85f660b7479de7aa559d79a
Gitweb: https://git.kernel.org/tip/4c4c6f38704ab0e3f85f660b7479de7aa559d79a
Author: Thomas Gleixner <[email protected]>
AuthorDate: Tue, 13 Feb 2024 22:05:47 +01:00
Committer: Thomas Gleixner <[email protected]>
CommitterDate: Thu, 15 Feb 2024 22:07:43 +01:00

x86/cpu/topology: Simplify APIC registration

Having the same check whether the number of assigned CPUs has reached the
nr_cpu_ids limit twice in the same code path is pointless. Repeating the
information that CPUs are ignored over and over is also pointless noise.

Remove the redundant check and reduce the noise by using a pr_warn_once().

Signed-off-by: Thomas Gleixner <[email protected]>
Tested-by: Michael Kelley <[email protected]>
Tested-by: Sohil Mehta <[email protected]>
Link: https://lore.kernel.org/r/[email protected]



---
arch/x86/kernel/cpu/topology.c | 23 +++--------------------
1 file changed, 3 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
index a6c9314..8b42918 100644
--- a/arch/x86/kernel/cpu/topology.c
+++ b/arch/x86/kernel/cpu/topology.c
@@ -107,14 +107,6 @@ static int allocate_logical_cpuid(u32 apic_id)
if (cpu >= 0)
return cpu;

- /* Allocate a new cpuid. */
- if (nr_logical_cpuids >= nr_cpu_ids) {
- WARN_ONCE(1, "APIC: NR_CPUS/possible_cpus limit of %u reached. "
- "Processor %d/0x%x and the rest are ignored.\n",
- nr_cpu_ids, nr_logical_cpuids, apic_id);
- return -EINVAL;
- }
-
cpuid_to_apicid[nr_logical_cpuids] = apic_id;
return nr_logical_cpuids++;
}
@@ -135,7 +127,7 @@ static void cpu_update_apic(int cpu, u32 apicid)

static int generic_processor_info(int apicid)
{
- int cpu, max = nr_cpu_ids;
+ int cpu;

/* The boot CPU must be set before MADT/MPTABLE parsing happens */
if (cpuid_to_apicid[0] == BAD_APICID)
@@ -155,21 +147,12 @@ static int generic_processor_info(int apicid)
}

if (num_processors >= nr_cpu_ids) {
- int thiscpu = max + disabled_cpus;
-
- pr_warn("APIC: NR_CPUS/possible_cpus limit of %i reached. "
- "Processor %d/0x%x ignored.\n", max, thiscpu, apicid);
-
+ pr_warn_once("APIC: CPU limit of %d reached. Ignoring further CPUs\n", nr_cpu_ids);
disabled_cpus++;
- return -EINVAL;
+ return -ENOSPC;
}

cpu = allocate_logical_cpuid(apicid);
- if (cpu < 0) {
- disabled_cpus++;
- return -EINVAL;
- }
-
cpu_update_apic(cpu, apicid);
return cpu;
}