From: Anton Blanchard <anton@samba.org>
To: benh@kernel.crashing.org, paulus@samba.org, hbabu@us.ibm.com
Cc: linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 2/9] powerpc: Remove broken and complicated kdump system reset code
Date: Wed, 30 Nov 2011 21:23:10 +1100 [thread overview]
Message-ID: <20111130102414.861342670@samba.org> (raw)
In-Reply-To: 20111130102308.348262468@samba.org
We have a lot of complicated logic that handles possible recursion between
kdump and a system reset exception. We can solve this in a much simpler
way using the same setjmp/longjmp tricks xmon does.
As a first step, this patch removes the old system reset code.
Signed-off-by: Anton Blanchard <anton@samba.org>
---
Index: linux-build/arch/powerpc/include/asm/kexec.h
===================================================================
--- linux-build.orig/arch/powerpc/include/asm/kexec.h 2011-11-09 16:27:35.918705307 +1100
+++ linux-build/arch/powerpc/include/asm/kexec.h 2011-11-14 08:31:02.111805931 +1100
@@ -73,11 +73,6 @@ extern void kexec_smp_wait(void); /* get
master to copy new code to 0 */
extern int crashing_cpu;
extern void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *));
-extern cpumask_t cpus_in_sr;
-static inline int kexec_sr_activated(int cpu)
-{
- return cpumask_test_cpu(cpu, &cpus_in_sr);
-}
struct kimage;
struct pt_regs;
@@ -94,7 +89,6 @@ extern void reserve_crashkernel(void);
extern void machine_kexec_mask_interrupts(void);
#else /* !CONFIG_KEXEC */
-static inline int kexec_sr_activated(int cpu) { return 0; }
static inline void crash_kexec_secondary(struct pt_regs *regs) { }
static inline int overlaps_crashkernel(unsigned long start, unsigned long size)
Index: linux-build/arch/powerpc/kernel/crash.c
===================================================================
--- linux-build.orig/arch/powerpc/kernel/crash.c 2011-11-09 16:27:35.950705892 +1100
+++ linux-build/arch/powerpc/kernel/crash.c 2011-11-14 08:31:02.111805931 +1100
@@ -47,7 +47,6 @@
/* This keeps a track of which one is crashing cpu. */
int crashing_cpu = -1;
static cpumask_t cpus_in_crash = CPU_MASK_NONE;
-cpumask_t cpus_in_sr = CPU_MASK_NONE;
#define CRASH_HANDLER_MAX 3
/* NULL terminated list of shutdown handles */
@@ -55,7 +54,6 @@ static crash_shutdown_t crash_shutdown_h
static DEFINE_SPINLOCK(crash_handlers_lock);
#ifdef CONFIG_SMP
-static atomic_t enter_on_soft_reset = ATOMIC_INIT(0);
void crash_ipi_callback(struct pt_regs *regs)
{
@@ -70,23 +68,8 @@ void crash_ipi_callback(struct pt_regs *
cpumask_set_cpu(cpu, &cpus_in_crash);
/*
- * Entered via soft-reset - could be the kdump
- * process is invoked using soft-reset or user activated
- * it if some CPU did not respond to an IPI.
- * For soft-reset, the secondary CPU can enter this func
- * twice. 1 - using IPI, and 2. soft-reset.
- * Tell the kexec CPU that entered via soft-reset and ready
- * to go down.
- */
- if (cpumask_test_cpu(cpu, &cpus_in_sr)) {
- cpumask_clear_cpu(cpu, &cpus_in_sr);
- atomic_inc(&enter_on_soft_reset);
- }
-
- /*
* Starting the kdump boot.
* This barrier is needed to make sure that all CPUs are stopped.
- * If not, soft-reset will be invoked to bring other CPUs.
*/
while (!cpumask_test_cpu(crashing_cpu, &cpus_in_crash))
cpu_relax();
@@ -103,25 +86,14 @@ void crash_ipi_callback(struct pt_regs *
/* NOTREACHED */
}
-/*
- * Wait until all CPUs are entered via soft-reset.
- */
-static void crash_soft_reset_check(int cpu)
-{
- unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
-
- cpumask_clear_cpu(cpu, &cpus_in_sr);
- while (atomic_read(&enter_on_soft_reset) != ncpus)
- cpu_relax();
-}
-
-
static void crash_kexec_prepare_cpus(int cpu)
{
unsigned int msecs;
unsigned int ncpus = num_online_cpus() - 1;/* Excluding the panic cpu */
+ printk(KERN_EMERG "Sending IPI to other CPUs\n");
+
crash_send_ipi(crash_ipi_callback);
smp_wmb();
@@ -131,7 +103,6 @@ static void crash_kexec_prepare_cpus(int
* respond.
* Delay of at least 10 seconds.
*/
- printk(KERN_EMERG "Sending IPI to other cpus...\n");
msecs = 10000;
while ((cpumask_weight(&cpus_in_crash) < ncpus) && (--msecs > 0)) {
cpu_relax();
@@ -140,69 +111,36 @@ static void crash_kexec_prepare_cpus(int
/* Would it be better to replace the trap vector here? */
- /*
- * FIXME: In case if we do not get all CPUs, one possibility: ask the
- * user to do soft reset such that we get all.
- * Soft-reset will be used until better mechanism is implemented.
- */
if (cpumask_weight(&cpus_in_crash) < ncpus) {
- printk(KERN_EMERG "done waiting: %d cpu(s) not responding\n",
+ printk(KERN_EMERG "ERROR: %d CPU(s) not responding\n",
ncpus - cpumask_weight(&cpus_in_crash));
- printk(KERN_EMERG "Activate soft-reset to stop other cpu(s)\n");
- cpumask_clear(&cpus_in_sr);
- atomic_set(&enter_on_soft_reset, 0);
- while (cpumask_weight(&cpus_in_crash) < ncpus)
- cpu_relax();
}
- /*
- * Make sure all CPUs are entered via soft-reset if the kdump is
- * invoked using soft-reset.
- */
- if (cpumask_test_cpu(cpu, &cpus_in_sr))
- crash_soft_reset_check(cpu);
- /* Leave the IPI callback set */
+
+ printk(KERN_EMERG "IPI complete\n");
}
/*
- * This function will be called by secondary cpus or by kexec cpu
- * if soft-reset is activated to stop some CPUs.
+ * This function will be called by secondary cpus.
*/
void crash_kexec_secondary(struct pt_regs *regs)
{
- int cpu = smp_processor_id();
unsigned long flags;
- int msecs = 5;
+ int msecs = 500;
local_irq_save(flags);
- /* Wait 5ms if the kexec CPU is not entered yet. */
+
+ /* Wait 500ms for the primary crash CPU to signal its progress */
while (crashing_cpu < 0) {
if (--msecs < 0) {
- /*
- * Either kdump image is not loaded or
- * kdump process is not started - Probably xmon
- * exited using 'x'(exit and recover) or
- * kexec_should_crash() failed for all running tasks.
- */
- cpumask_clear_cpu(cpu, &cpus_in_sr);
+ /* No response, kdump image may not have been loaded */
local_irq_restore(flags);
return;
}
+
mdelay(1);
cpu_relax();
}
- if (cpu == crashing_cpu) {
- /*
- * Panic CPU will enter this func only via soft-reset.
- * Wait until all secondary CPUs entered and
- * then start kexec boot.
- */
- crash_soft_reset_check(cpu);
- cpumask_set_cpu(crashing_cpu, &cpus_in_crash);
- if (ppc_md.kexec_cpu_down)
- ppc_md.kexec_cpu_down(1, 0);
- machine_kexec(kexec_crash_image);
- /* NOTREACHED */
- }
+
crash_ipi_callback(regs);
}
@@ -225,7 +163,6 @@ static void crash_kexec_prepare_cpus(int
void crash_kexec_secondary(struct pt_regs *regs)
{
- cpumask_clear(&cpus_in_sr);
}
#endif /* CONFIG_SMP */
Index: linux-build/arch/powerpc/kernel/traps.c
===================================================================
--- linux-build.orig/arch/powerpc/kernel/traps.c 2011-11-14 08:31:01.519795547 +1100
+++ linux-build/arch/powerpc/kernel/traps.c 2011-11-14 08:31:02.111805931 +1100
@@ -162,10 +162,20 @@ int die(const char *str, struct pt_regs
printk("\n");
raw_spin_unlock_irqrestore(&die.lock, flags);
- if (kexec_should_crash(current) ||
- kexec_sr_activated(smp_processor_id()))
+ /*
+ * A system reset (0x100) is a request to dump, so we always send
+ * it through the crashdump code.
+ */
+ if (kexec_should_crash(current) || (TRAP(regs) == 0x100)) {
crash_kexec(regs);
- crash_kexec_secondary(regs);
+
+ /*
+ * We aren't the primary crash CPU. We need to send it
+ * to a holding pattern to avoid it ending up in the panic
+ * code.
+ */
+ crash_kexec_secondary(regs);
+ }
/*
* While our oops output is serialised by a spinlock, output
@@ -232,25 +242,8 @@ void system_reset_exception(struct pt_re
return;
}
-#ifdef CONFIG_KEXEC
- cpumask_set_cpu(smp_processor_id(), &cpus_in_sr);
-#endif
-
die("System Reset", regs, SIGABRT);
- /*
- * Some CPUs when released from the debugger will execute this path.
- * These CPUs entered the debugger via a soft-reset. If the CPU was
- * hung before entering the debugger it will return to the hung
- * state when exiting this function. This causes a problem in
- * kdump since the hung CPU(s) will not respond to the IPI sent
- * from kdump. To prevent the problem we call crash_kexec_secondary()
- * here. If a kdump had not been initiated or we exit the debugger
- * with the "exit and recover" command (x) crash_kexec_secondary()
- * will return after 5ms and the CPU returns to its previous state.
- */
- crash_kexec_secondary(regs);
-
/* Must die if the interrupt is not recoverable */
if (!(regs->msr & MSR_RI))
panic("Unrecoverable System Reset");
next prev parent reply other threads:[~2011-11-30 10:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-30 10:23 [PATCH 0/9] oops and kdump patches Anton Blanchard
2011-11-30 10:23 ` [PATCH 1/9] powerpc: Give us time to get all oopses out before panicking Anton Blanchard
2011-11-30 10:23 ` Anton Blanchard [this message]
2011-11-30 10:23 ` [PATCH 3/9] powerpc/kdump: Use setjmp/longjmp to handle kdump and system reset recursion Anton Blanchard
2011-11-30 10:23 ` [PATCH 4/9] powerpc: Cleanup crash/kexec code Anton Blanchard
2011-11-30 10:23 ` [PATCH 5/9] powerpc: Rework die() Anton Blanchard
2011-11-30 10:23 ` [PATCH 6/9] powerpc: Reduce pseries panic timeout from 180s to 10s Anton Blanchard
2011-11-30 10:23 ` [PATCH 7/9] powerpc/xics: Reset the CPPR if H_EOI fails Anton Blanchard
2011-11-30 10:23 ` [PATCH 8/9] powerpc/kdump: Delay before sending IPI on a system reset Anton Blanchard
2011-11-30 10:23 ` [PATCH 9/9] powerpc/kdump: Only save CPU state first time through the secondary CPU capture code Anton Blanchard
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