linux-kernel - [tip: x86/apic] x86/cpu/topology: Simplify APIC registration

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Date: Fri, 16 Feb 2024 15:17:01 -0000
From: "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
 Michael Kelley <mhklinux@...look.com>, Sohil Mehta <sohil.mehta@...el.com>,
 x86@...nel.org, linux-kernel@...r.kernel.org
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 <tglx@...utronix.de>
AuthorDate:    Tue, 13 Feb 2024 22:05:47 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
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 <tglx@...utronix.de>
Tested-by: Michael Kelley <mhklinux@...look.com>
Tested-by: Sohil Mehta <sohil.mehta@...el.com>
Link: https://lore.kernel.org/r/20240213210252.050264369@linutronix.de



---
 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;
 }