Date: Mon, 12 Jan 2026 04:05:27 +0000 From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: fe3001bde484 - stable/15 - x86: change ap_boot_mtx from spinlock mutex to naive lock Message-ID: <69647307.20473.4c77b380@gitrepo.freebsd.org>
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The branch stable/15 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=fe3001bde4849757064e8bb63fdab8b3b797dd6d commit fe3001bde4849757064e8bb63fdab8b3b797dd6d Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2026-01-03 01:09:32 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2026-01-12 04:05:08 +0000 x86: change ap_boot_mtx from spinlock mutex to naive lock PR: 289297 (cherry picked from commit 55305b590797524dd1cecfc9406869700e925e51) --- sys/amd64/amd64/mp_machdep.c | 1 - sys/i386/i386/mp_machdep.c | 2 -- sys/x86/include/x86_smp.h | 1 - sys/x86/x86/mp_x86.c | 17 ++++++++++++----- 4 files changed, 12 insertions(+), 9 deletions(-) diff --git a/sys/amd64/amd64/mp_machdep.c b/sys/amd64/amd64/mp_machdep.c index 00e99f9df192..9af87787e7cc 100644 --- a/sys/amd64/amd64/mp_machdep.c +++ b/sys/amd64/amd64/mp_machdep.c @@ -331,7 +331,6 @@ start_all_aps(void) u_char mpbiosreason; amd64_mp_alloc_pcpu(); - mtx_init(&ap_boot_mtx, "ap boot", NULL, MTX_SPIN); MPASS(bootMP_size <= PAGE_SIZE); m_boottramp = vm_page_alloc_noobj_contig(0, 1, 0, diff --git a/sys/i386/i386/mp_machdep.c b/sys/i386/i386/mp_machdep.c index f7d9289b1848..18ec0d83fad3 100644 --- a/sys/i386/i386/mp_machdep.c +++ b/sys/i386/i386/mp_machdep.c @@ -369,8 +369,6 @@ start_all_aps(void) u_int32_t mpbioswarmvec; int apic_id, cpu; - mtx_init(&ap_boot_mtx, "ap boot", NULL, MTX_SPIN); - pmap_remap_lower(true); /* install the AP 1st level boot code */ diff --git a/sys/x86/include/x86_smp.h b/sys/x86/include/x86_smp.h index 8b9eb2ec9b66..5cecfab9d183 100644 --- a/sys/x86/include/x86_smp.h +++ b/sys/x86/include/x86_smp.h @@ -35,7 +35,6 @@ extern char *bootSTK; extern void *bootstacks[]; extern unsigned int bootMP_size; extern volatile int aps_ready; -extern struct mtx ap_boot_mtx; extern int cpu_logical; extern int cpu_cores; extern volatile uint32_t smp_tlb_generation; diff --git a/sys/x86/x86/mp_x86.c b/sys/x86/x86/mp_x86.c index c0da41a4d222..8345117f5b6f 100644 --- a/sys/x86/x86/mp_x86.c +++ b/sys/x86/x86/mp_x86.c @@ -124,7 +124,7 @@ volatile cpuset_t resuming_cpus; volatile cpuset_t toresume_cpus; /* used to hold the AP's until we are ready to release them */ -struct mtx ap_boot_mtx; +static int ap_boot_lock; /* Set to 1 once we're ready to let the APs out of the pen. */ volatile int aps_ready = 0; @@ -1086,8 +1086,6 @@ init_secondary_tail(void) PCPU_SET(curthread, PCPU_GET(idlethread)); schedinit_ap(); - mtx_lock_spin(&ap_boot_mtx); - mca_init(); /* Init local apic for irq's */ @@ -1096,6 +1094,15 @@ init_secondary_tail(void) /* Set memory range attributes for this CPU to match the BSP */ mem_range_AP_init(); + /* + * Use naive spinning lock instead of the real spinlock, since + * printfs() below might take a very long time and trigger + * spinlock timeout panics. This is the only use of the + * ap_boot_lock anyway. + */ + while (atomic_cmpset_acq_int(&ap_boot_lock, 0, 1) == 0) + ia32_pause(); + smp_cpus++; CTR1(KTR_SMP, "SMP: AP CPU #%d Launched", cpuid); @@ -1117,6 +1124,8 @@ init_secondary_tail(void) atomic_store_rel_int(&smp_started, 1); } + atomic_store_rel_int(&ap_boot_lock, 0); + #ifdef __amd64__ if (pmap_pcid_enabled) load_cr4(rcr4() | CR4_PCIDE); @@ -1125,8 +1134,6 @@ init_secondary_tail(void) load_fs(_ufssel); #endif - mtx_unlock_spin(&ap_boot_mtx); - /* Wait until all the AP's are up. */ while (atomic_load_acq_int(&smp_started) == 0) ia32_pause();home | help
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