Patches contributed by Eötvös Lorand University
commit 6ebf622b2577c50b1f496bd6a5e8739e55ae7b1c
Author: Ingo Molnar <mingo@elte.hu>
Date: Mon Mar 5 13:20:11 2007 +0100
[PATCH] disable NMI watchdog by default
there's a new NMI watchdog related problem: KVM crashes on certain
bzImages because ... we enable the NMI watchdog by default (even if the
user does not ask for it) , and no other OS on this planet does that so
KVM doesnt have emulation for that yet. So KVM injects a #GP, which
crashes the Linux guest:
general protection fault: 0000 [#1]
PREEMPT SMP
Modules linked in:
CPU: 0
EIP: 0060:[<c011a8ae>] Not tainted VLI
EFLAGS: 00000246 (2.6.20-rc5-rt0 #3)
EIP is at setup_apic_nmi_watchdog+0x26d/0x3d3
and no, i did /not/ request an nmi_watchdog on the boot command line!
Solution: turn off that darn thing! It's a debug tool, not a 'make life
harder' tool!!
with this patch the KVM guest boots up just fine.
And with this my laptop (Lenovo T60) also stopped its sporadic hard
hanging (sometimes in acpi_init(), sometimes later during bootup,
sometimes much later during actual use) as well. It hung with both
nmi_watchdog=1 and nmi_watchdog=2, so it's generally the fact of NMI
injection that is causing problems, not the NMI watchdog variant, nor
any particular bootup code.
[ NMI breaks on some systems, esp in combination with SMM -Arjan ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/asm-i386/nmi.h b/include/asm-i386/nmi.h
index b04333ea6f31..64544cb85d6a 100644
--- a/include/asm-i386/nmi.h
+++ b/include/asm-i386/nmi.h
@@ -33,7 +33,7 @@ extern int nmi_watchdog_tick (struct pt_regs * regs, unsigned reason);
extern atomic_t nmi_active;
extern unsigned int nmi_watchdog;
-#define NMI_DEFAULT -1
+#define NMI_DEFAULT 0
#define NMI_NONE 0
#define NMI_IO_APIC 1
#define NMI_LOCAL_APIC 2
diff --git a/include/asm-x86_64/nmi.h b/include/asm-x86_64/nmi.h
index 72375e7d32a8..ceb3d8dac33d 100644
--- a/include/asm-x86_64/nmi.h
+++ b/include/asm-x86_64/nmi.h
@@ -64,7 +64,7 @@ extern int setup_nmi_watchdog(char *);
extern atomic_t nmi_active;
extern unsigned int nmi_watchdog;
-#define NMI_DEFAULT -1
+#define NMI_DEFAULT 0
#define NMI_NONE 0
#define NMI_IO_APIC 1
#define NMI_LOCAL_APIC 2
commit 0d05ad2c09af9fb33ae76f9f8d1c4e4d1a9de92c
Author: Ingo Molnar <mingo@elte.hu>
Date: Mon Mar 5 13:15:40 2007 +0100
[PATCH] paravirt: let users decide whether they want VMI
do not use default=y for CONFIG_VMI (we do not do that for any driver or
special-hardware feature): the overwhelming majority of Linux users does
not need it, and interested users and distributions can enable it
as-needed.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index cfc5d496fffb..cee4ff679d3c 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -221,7 +221,6 @@ config PARAVIRT
config VMI
bool "VMI Paravirt-ops support"
depends on PARAVIRT
- default y
help
VMI provides a paravirtualized interface to the VMware ESX server
(it could be used by other hypervisors in theory too, but is not
commit e9417fb324f355e8e0b5d78d3b5dc7b90693fdfb
Author: Ingo Molnar <mingo@elte.hu>
Date: Mon Mar 5 13:13:46 2007 +0100
[PATCH] paravirt: clarify VMI description
Clarify the description of the CONFIG_VMI option: describe the reality
that VMI is a VMWare-only interface for now. Once that changes and
another hypervisor adopts the VMI ABI we can change the text.
As can be seen from the Xen paravirtualization patches submitted to lkml
the Xen project has chosen its own, non-VMI interface between Xen and
the para-Linux - so remove Xen from the description.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 065903886624..cfc5d496fffb 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -223,8 +223,9 @@ config VMI
depends on PARAVIRT
default y
help
- VMI provides a paravirtualized interface to multiple hypervisors
- include VMware ESX server and Xen by connecting to a ROM module
+ VMI provides a paravirtualized interface to the VMware ESX server
+ (it could be used by other hypervisors in theory too, but is not
+ at the moment), by linking the kernel to a GPL-ed ROM module
provided by the hypervisor.
config ACPI_SRAT
commit 3f1a73b6dd52f1f279c05263ee79ca14f45d9d25
Author: Ingo Molnar <mingo@elte.hu>
Date: Mon Mar 5 12:29:28 2007 +0100
[PATCH] paravirt: remove NO_IDLE_HZ on x86
Temove the mistaken turning on of NO_IDLE_HZ on x86+PARAVIRT kernels.
It's an obsolete, limited form of dynticks.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index e970887b9e69..065903886624 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -1287,12 +1287,3 @@ config X86_TRAMPOLINE
config KTIME_SCALAR
bool
default y
-
-config NO_IDLE_HZ
- bool
- depends on PARAVIRT
- default y
- help
- Switches the regular HZ timer off when the system is going idle.
- This helps a hypervisor detect that the Linux system is idle,
- reducing the overhead of idle systems.
commit c21415e84334af679630f6450ceb8929a5234fad
Author: Ingo Molnar <mingo@elte.hu>
Date: Mon Feb 19 14:37:47 2007 +0200
KVM: Add host hypercall support for vmx
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 0198d400037f..ca79e594ea6e 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1657,6 +1657,20 @@ static int handle_halt(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
return 0;
}
+static int handle_vmcall(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
+{
+ kvm_run->exit_reason = KVM_EXIT_DEBUG;
+ printk(KERN_DEBUG "got vmcall at RIP %08lx\n", vmcs_readl(GUEST_RIP));
+ printk(KERN_DEBUG "vmcall params: %08lx, %08lx, %08lx, %08lx\n",
+ vcpu->regs[VCPU_REGS_RAX],
+ vcpu->regs[VCPU_REGS_RCX],
+ vcpu->regs[VCPU_REGS_RDX],
+ vcpu->regs[VCPU_REGS_RBP]);
+ vcpu->regs[VCPU_REGS_RAX] = 0;
+ vmcs_writel(GUEST_RIP, vmcs_readl(GUEST_RIP)+3);
+ return 1;
+}
+
/*
* The exit handlers return 1 if the exit was handled fully and guest execution
* may resume. Otherwise they set the kvm_run parameter to indicate what needs
@@ -1675,6 +1689,7 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu,
[EXIT_REASON_MSR_WRITE] = handle_wrmsr,
[EXIT_REASON_PENDING_INTERRUPT] = handle_interrupt_window,
[EXIT_REASON_HLT] = handle_halt,
+ [EXIT_REASON_VMCALL] = handle_vmcall,
};
static const int kvm_vmx_max_exit_handlers =
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index 74be5c1002ec..3b292565a693 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -52,4 +52,22 @@ struct kvm_vcpu_para_state {
#define KVM_EINVAL 1
+/*
+ * Hypercall calling convention:
+ *
+ * Each hypercall may have 0-6 parameters.
+ *
+ * 64-bit hypercall index is in RAX, goes from 0 to __NR_hypercalls-1
+ *
+ * 64-bit parameters 1-6 are in the standard gcc x86_64 calling convention
+ * order: RDI, RSI, RDX, RCX, R8, R9.
+ *
+ * 32-bit index is EBX, parameters are: EAX, ECX, EDX, ESI, EDI, EBP.
+ * (the first 3 are according to the gcc regparm calling convention)
+ *
+ * No registers are clobbered by the hypercall, except that the
+ * return value is in RAX.
+ */
+#define __NR_hypercalls 0
+
#endif
commit 102d8325a1d2f266d3d0a03fdde948544e72c12d
Author: Ingo Molnar <mingo@elte.hu>
Date: Mon Feb 19 14:37:47 2007 +0200
KVM: add MSR based hypercall API
This adds a special MSR based hypercall API to KVM. This is to be
used by paravirtual kernels and virtual drivers.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 9a49b2ed2a1e..fd7746a2bc3e 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -14,6 +14,7 @@
#include "vmx.h"
#include <linux/kvm.h>
+#include <linux/kvm_para.h>
#define CR0_PE_MASK (1ULL << 0)
#define CR0_TS_MASK (1ULL << 3)
@@ -237,6 +238,9 @@ struct kvm_vcpu {
unsigned long cr0;
unsigned long cr2;
unsigned long cr3;
+ gpa_t para_state_gpa;
+ struct page *para_state_page;
+ gpa_t hypercall_gpa;
unsigned long cr4;
unsigned long cr8;
u64 pdptrs[4]; /* pae */
@@ -382,6 +386,8 @@ struct kvm_arch_ops {
int (*run)(struct kvm_vcpu *vcpu, struct kvm_run *run);
int (*vcpu_setup)(struct kvm_vcpu *vcpu);
void (*skip_emulated_instruction)(struct kvm_vcpu *vcpu);
+ void (*patch_hypercall)(struct kvm_vcpu *vcpu,
+ unsigned char *hypercall_addr);
};
extern struct kvm_stat kvm_stat;
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 122c05f283e1..757a41f1db84 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -1204,6 +1204,73 @@ void realmode_set_cr(struct kvm_vcpu *vcpu, int cr, unsigned long val,
}
}
+/*
+ * Register the para guest with the host:
+ */
+static int vcpu_register_para(struct kvm_vcpu *vcpu, gpa_t para_state_gpa)
+{
+ struct kvm_vcpu_para_state *para_state;
+ hpa_t para_state_hpa, hypercall_hpa;
+ struct page *para_state_page;
+ unsigned char *hypercall;
+ gpa_t hypercall_gpa;
+
+ printk(KERN_DEBUG "kvm: guest trying to enter paravirtual mode\n");
+ printk(KERN_DEBUG ".... para_state_gpa: %08Lx\n", para_state_gpa);
+
+ /*
+ * Needs to be page aligned:
+ */
+ if (para_state_gpa != PAGE_ALIGN(para_state_gpa))
+ goto err_gp;
+
+ para_state_hpa = gpa_to_hpa(vcpu, para_state_gpa);
+ printk(KERN_DEBUG ".... para_state_hpa: %08Lx\n", para_state_hpa);
+ if (is_error_hpa(para_state_hpa))
+ goto err_gp;
+
+ para_state_page = pfn_to_page(para_state_hpa >> PAGE_SHIFT);
+ para_state = kmap_atomic(para_state_page, KM_USER0);
+
+ printk(KERN_DEBUG ".... guest version: %d\n", para_state->guest_version);
+ printk(KERN_DEBUG ".... size: %d\n", para_state->size);
+
+ para_state->host_version = KVM_PARA_API_VERSION;
+ /*
+ * We cannot support guests that try to register themselves
+ * with a newer API version than the host supports:
+ */
+ if (para_state->guest_version > KVM_PARA_API_VERSION) {
+ para_state->ret = -KVM_EINVAL;
+ goto err_kunmap_skip;
+ }
+
+ hypercall_gpa = para_state->hypercall_gpa;
+ hypercall_hpa = gpa_to_hpa(vcpu, hypercall_gpa);
+ printk(KERN_DEBUG ".... hypercall_hpa: %08Lx\n", hypercall_hpa);
+ if (is_error_hpa(hypercall_hpa)) {
+ para_state->ret = -KVM_EINVAL;
+ goto err_kunmap_skip;
+ }
+
+ printk(KERN_DEBUG "kvm: para guest successfully registered.\n");
+ vcpu->para_state_page = para_state_page;
+ vcpu->para_state_gpa = para_state_gpa;
+ vcpu->hypercall_gpa = hypercall_gpa;
+
+ hypercall = kmap_atomic(pfn_to_page(hypercall_hpa >> PAGE_SHIFT),
+ KM_USER1) + (hypercall_hpa & ~PAGE_MASK);
+ kvm_arch_ops->patch_hypercall(vcpu, hypercall);
+ kunmap_atomic(hypercall, KM_USER1);
+
+ para_state->ret = 0;
+err_kunmap_skip:
+ kunmap_atomic(para_state, KM_USER0);
+ return 0;
+err_gp:
+ return 1;
+}
+
int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
{
u64 data;
@@ -1312,6 +1379,12 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
case MSR_IA32_MISC_ENABLE:
vcpu->ia32_misc_enable_msr = data;
break;
+ /*
+ * This is the 'probe whether the host is KVM' logic:
+ */
+ case MSR_KVM_API_MAGIC:
+ return vcpu_register_para(vcpu, data);
+
default:
printk(KERN_ERR "kvm: unhandled wrmsr: 0x%x\n", msr);
return 1;
diff --git a/drivers/kvm/svm.c b/drivers/kvm/svm.c
index 72cac0488b31..f6e86528f031 100644
--- a/drivers/kvm/svm.c
+++ b/drivers/kvm/svm.c
@@ -1669,6 +1669,18 @@ static int is_disabled(void)
return 0;
}
+static void
+svm_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall)
+{
+ /*
+ * Patch in the VMMCALL instruction:
+ */
+ hypercall[0] = 0x0f;
+ hypercall[1] = 0x01;
+ hypercall[2] = 0xd9;
+ hypercall[3] = 0xc3;
+}
+
static struct kvm_arch_ops svm_arch_ops = {
.cpu_has_kvm_support = has_svm,
.disabled_by_bios = is_disabled,
@@ -1717,6 +1729,7 @@ static struct kvm_arch_ops svm_arch_ops = {
.run = svm_vcpu_run,
.skip_emulated_instruction = skip_emulated_instruction,
.vcpu_setup = svm_vcpu_setup,
+ .patch_hypercall = svm_patch_hypercall,
};
static int __init svm_init(void)
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index d1198e2b2b5d..0198d400037f 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1469,6 +1469,18 @@ static int handle_io(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
return 0;
}
+static void
+vmx_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall)
+{
+ /*
+ * Patch in the VMCALL instruction:
+ */
+ hypercall[0] = 0x0f;
+ hypercall[1] = 0x01;
+ hypercall[2] = 0xc1;
+ hypercall[3] = 0xc3;
+}
+
static int handle_cr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
u64 exit_qualification;
@@ -2064,6 +2076,7 @@ static struct kvm_arch_ops vmx_arch_ops = {
.run = vmx_vcpu_run,
.skip_emulated_instruction = skip_emulated_instruction,
.vcpu_setup = vmx_vcpu_setup,
+ .patch_hypercall = vmx_patch_hypercall,
};
static int __init vmx_init(void)
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
new file mode 100644
index 000000000000..74be5c1002ec
--- /dev/null
+++ b/include/linux/kvm_para.h
@@ -0,0 +1,55 @@
+#ifndef __LINUX_KVM_PARA_H
+#define __LINUX_KVM_PARA_H
+
+/*
+ * Guest OS interface for KVM paravirtualization
+ *
+ * Note: this interface is totally experimental, and is certain to change
+ * as we make progress.
+ */
+
+/*
+ * Per-VCPU descriptor area shared between guest and host. Writable to
+ * both guest and host. Registered with the host by the guest when
+ * a guest acknowledges paravirtual mode.
+ *
+ * NOTE: all addresses are guest-physical addresses (gpa), to make it
+ * easier for the hypervisor to map between the various addresses.
+ */
+struct kvm_vcpu_para_state {
+ /*
+ * API version information for compatibility. If there's any support
+ * mismatch (too old host trying to execute too new guest) then
+ * the host will deny entry into paravirtual mode. Any other
+ * combination (new host + old guest and new host + new guest)
+ * is supposed to work - new host versions will support all old
+ * guest API versions.
+ */
+ u32 guest_version;
+ u32 host_version;
+ u32 size;
+ u32 ret;
+
+ /*
+ * The address of the vm exit instruction (VMCALL or VMMCALL),
+ * which the host will patch according to the CPU model the
+ * VM runs on:
+ */
+ u64 hypercall_gpa;
+
+} __attribute__ ((aligned(PAGE_SIZE)));
+
+#define KVM_PARA_API_VERSION 1
+
+/*
+ * This is used for an RDMSR's ECX parameter to probe for a KVM host.
+ * Hopefully no CPU vendor will use up this number. This is placed well
+ * out of way of the typical space occupied by CPU vendors' MSR indices,
+ * and we think (or at least hope) it wont be occupied in the future
+ * either.
+ */
+#define MSR_KVM_API_MAGIC 0x87655678
+
+#define KVM_EINVAL 1
+
+#endif
commit 7355690ead6d61f6344072ae61060f985060da29
Author: Ingo Molnar <mingo@elte.hu>
Date: Wed Feb 28 20:13:42 2007 -0800
[PATCH] sched: fix SMT scheduler bug
The SMT scheduler incorrectly skips kernel threads even if they are
runnable (but they are preempted by a higher-prio user-space task which got
SMT-delayed by an even higher-priority task running on a sibling CPU).
Fix this for now by only doing the SMT-nice optimization if the
to-be-delayed task is the only runnable task. (This should cover most of
the real-life cases anyway.)
This bug has been in the SMT scheduler since 2.6.17 or so, but has only
been noticed now by the active check in the dynticks code.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/sched.c b/kernel/sched.c
index 0c5ebf59b8bc..5f102e6c7a4c 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -3547,7 +3547,7 @@ asmlinkage void __sched schedule(void)
}
}
next->sleep_type = SLEEP_NORMAL;
- if (dependent_sleeper(cpu, rq, next))
+ if (rq->nr_running == 1 && dependent_sleeper(cpu, rq, next))
next = rq->idle;
switch_tasks:
if (next == rq->idle)
commit 25165120f2432ffa36518d53bd3ec66f6e434f63
Author: Ingo Molnar <mingo@elte.hu>
Date: Thu Feb 22 09:38:22 2007 +0100
[PATCH] x86: add -freg-struct-return to CFLAGS
Jeremy Fitzhardinge suggested the use of -freg-struct-return, which does
structure-returns (such as when using pte_t) in registers instead of on
the stack.
that is indeed so, and this option reduced the kernel size a bit:
text data bss dec hex filename
4799506 543456 3760128 9103090 8ae6f2 vmlinux.before
4798117 543456 3760128 9101701 8ae185 vmlinux.after
the resulting kernel booted fine on my testbox. Lets go for it.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/i386/Makefile b/arch/i386/Makefile
index f7ac1aea1d8a..bd28f9f9b4b7 100644
--- a/arch/i386/Makefile
+++ b/arch/i386/Makefile
@@ -31,7 +31,7 @@ LDFLAGS_vmlinux := --emit-relocs
endif
CHECKFLAGS += -D__i386__
-CFLAGS += -pipe -msoft-float -mregparm=3
+CFLAGS += -pipe -msoft-float -mregparm=3 -freg-struct-return
# prevent gcc from keeping the stack 16 byte aligned
CFLAGS += $(call cc-option,-mpreferred-stack-boundary=2)
commit 38bed5429987c939d86cd3da915d6706fd1e6e53
Author: Ingo Molnar <mingo@elte.hu>
Date: Thu Feb 22 09:09:34 2007 +0100
[PATCH] add MAINTAINERS entry for high-res timers, clockevents, dynticks
Thomas is the maintainer and primary author of the high-res timers,
clockevents and dynticks code.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/MAINTAINERS b/MAINTAINERS
index a9c13196f6bd..10054b4078d0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1494,6 +1494,12 @@ M: jkosina@suse.cz
L: linux-input@atrey.karlin.mff.cuni.cz
S: Maintained
+HIGH-RESOLUTION TIMERS, CLOCKEVENTS, DYNTICKS
+P: Thomas Gleixner
+M: tglx@linutronix.de
+L: linux-kernel@vger.kernel.org
+S: Maintained
+
HIGH-SPEED SCC DRIVER FOR AX.25
P: Klaus Kudielka
M: klaus.kudielka@ieee.org
commit 6ba9b346e1e0eca65ec589d32de3a9fe32dc5de6
Author: Ingo Molnar <mingo@elte.hu>
Date: Mon Feb 19 18:11:56 2007 +0000
[PATCH] NOHZ: Fix RCU handling
When a CPU is needed for RCU the tick has to continue even when it was
stopped before.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 95e41f7f850b..9234e44fc94a 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -191,19 +191,19 @@ void tick_nohz_stop_sched_tick(void)
next_jiffies = get_next_timer_interrupt(last_jiffies);
delta_jiffies = next_jiffies - last_jiffies;
+ if (rcu_needs_cpu(cpu))
+ delta_jiffies = 1;
/*
* Do not stop the tick, if we are only one off
* or if the cpu is required for rcu
*/
- if (!ts->tick_stopped && (delta_jiffies == 1 || rcu_needs_cpu(cpu)))
+ if (!ts->tick_stopped && delta_jiffies == 1)
goto out;
/* Schedule the tick, if we are at least one jiffie off */
if ((long)delta_jiffies >= 1) {
- if (rcu_needs_cpu(cpu))
- delta_jiffies = 1;
- else
+ if (delta_jiffies > 1)
cpu_set(cpu, nohz_cpu_mask);
/*
* nohz_stop_sched_tick can be called several times before