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Commit fe1ffafa authored by Pekka Paalanen's avatar Pekka Paalanen Committed by Thomas Gleixner
Browse files

x86 mmiotrace: fix relay-buffer-full flag for SMP 



Relay has per-cpu buffers, but mmiotrace was using only a single flag
for detecting buffer full/not-full transitions. The new code makes
this per-cpu and actually counts missed events.

Signed-off-by: default avatarPekka Paalanen <pq@iki.fi>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 75bb8835

arch/x86/kernel/mmiotrace/mmio-mod.c

+16 −10
Original line number Original line Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <asm/pgtable.h>

#include <asm/pgtable.h>

#include <linux/mmiotrace.h>

#include <linux/mmiotrace.h>

#include <asm/e820.h> /* for ISA_START_ADDRESS */

#include <asm/e820.h> /* for ISA_START_ADDRESS */

#include <asm/atomic.h>





#include "kmmio.h"

#include "kmmio.h"

#include "pf_in.h"

#include "pf_in.h"
@@ -47,9 +48,13 @@ struct trap_reason { 
	int active_traces;

	int active_traces;

};

};





/* Accessed per-cpu. */

static struct trap_reason pf_reason[NR_CPUS];

static struct trap_reason pf_reason[NR_CPUS];

static struct mm_io_header_rw cpu_trace[NR_CPUS];

static struct mm_io_header_rw cpu_trace[NR_CPUS];





/* Access to this is not per-cpu. */

static atomic_t dropped[NR_CPUS];



static struct file_operations mmio_fops = {

static struct file_operations mmio_fops = {

	.owner = THIS_MODULE,

	.owner = THIS_MODULE,

};

};
@@ -57,7 +62,6 @@ static struct file_operations mmio_fops = { 
static const size_t subbuf_size = 256*1024;

static const size_t subbuf_size = 256*1024;

static struct rchan *chan;

static struct rchan *chan;

static struct dentry *dir;

static struct dentry *dir;

static int suspended;      /* XXX should this be per cpu? */

static struct proc_dir_entry *proc_marker_file;

static struct proc_dir_entry *proc_marker_file;





/* module parameters */

/* module parameters */
@@ -269,19 +273,21 @@ static void post(struct kmmio_probe *p, unsigned long condition, 
static int subbuf_start_handler(struct rchan_buf *buf, void *subbuf,

static int subbuf_start_handler(struct rchan_buf *buf, void *subbuf,

					void *prev_subbuf, size_t prev_padding)

					void *prev_subbuf, size_t prev_padding)

{

{

	unsigned int cpu = buf->cpu;

	atomic_t *drop = &dropped[cpu];

	int count;

	if (relay_buf_full(buf)) {

	if (relay_buf_full(buf)) {

		if (!suspended) {

		if (atomic_inc_return(drop) == 1) {

			suspended = 1;

			printk(KERN_ERR MODULE_NAME ": cpu %d buffer full!\n",

			printk(KERN_ERR MODULE_NAME

									cpu);

						": cpu %d buffer full!!!\n",

						smp_processor_id());

		}

		}

		return 0;

		return 0;

	} else if (suspended) {

	} else if ((count = atomic_read(drop))) {

		suspended = 0;

		printk(KERN_ERR MODULE_NAME

		printk(KERN_ERR MODULE_NAME

					": cpu %d buffer no longer full.\n",

					": cpu %d buffer no longer full, "

					smp_processor_id());

					"missed %d events.\n",

					cpu, count);

		atomic_sub(count, drop);

	}

	}





	return 1;

	return 1;