Commit ded85c19 authored by Hannes Reinecke's avatar Hannes Reinecke Committed by Christoph Hellwig

scsi: Implement per-cpu logging buffer

Implement a per-cpu buffer for formatting messages to avoid line breaks
up under high load.  This patch implements scmd_printk() and
sdev_prefix_printk() using the per-cpu buffer and makes sdev_printk() a
wrapper for sdev_prefix_printk().
Tested-by: default avatarRobert Elliott <elliott@hp.com>
Reviewed-by: default avatarRobert Elliott <elliott@hp.com>
Signed-off-by: default avatarHannes Reinecke <hare@suse.de>
Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
parent b0a93d96
......@@ -167,7 +167,7 @@ scsi_mod-y += scsi_scan.o scsi_sysfs.o scsi_devinfo.o
scsi_mod-$(CONFIG_SCSI_NETLINK) += scsi_netlink.o
scsi_mod-$(CONFIG_SYSCTL) += scsi_sysctl.o
scsi_mod-$(CONFIG_SCSI_PROC_FS) += scsi_proc.o
scsi_mod-y += scsi_trace.o
scsi_mod-y += scsi_trace.o scsi_logging.o
scsi_mod-$(CONFIG_PM) += scsi_pm.o
hv_storvsc-y := storvsc_drv.o
......
/*
* scsi_logging.c
*
* Copyright (C) 2014 SUSE Linux Products GmbH
* Copyright (C) 2014 Hannes Reinecke <hare@suse.de>
*
* This file is released under the GPLv2
*/
#include <linux/kernel.h>
#include <linux/atomic.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_dbg.h>
#define SCSI_LOG_SPOOLSIZE 4096
#define SCSI_LOG_BUFSIZE 128
#if (SCSI_LOG_SPOOLSIZE / SCSI_LOG_BUFSIZE) > BITS_PER_LONG
#warning SCSI logging bitmask too large
#endif
struct scsi_log_buf {
char buffer[SCSI_LOG_SPOOLSIZE];
unsigned long map;
};
static DEFINE_PER_CPU(struct scsi_log_buf, scsi_format_log);
static char *scsi_log_reserve_buffer(size_t *len)
{
struct scsi_log_buf *buf;
unsigned long map_bits = sizeof(buf->buffer) / SCSI_LOG_BUFSIZE;
unsigned long idx = 0;
preempt_disable();
buf = this_cpu_ptr(&scsi_format_log);
idx = find_first_zero_bit(&buf->map, map_bits);
if (likely(idx < map_bits)) {
while (test_and_set_bit(idx, &buf->map)) {
idx = find_next_zero_bit(&buf->map, map_bits, idx);
if (idx >= map_bits)
break;
}
}
if (WARN_ON(idx >= map_bits)) {
preempt_enable();
return NULL;
}
*len = SCSI_LOG_BUFSIZE;
return buf->buffer + idx * SCSI_LOG_BUFSIZE;
}
static void scsi_log_release_buffer(char *bufptr)
{
struct scsi_log_buf *buf;
unsigned long idx;
int ret;
buf = this_cpu_ptr(&scsi_format_log);
if (bufptr >= buf->buffer &&
bufptr < buf->buffer + SCSI_LOG_SPOOLSIZE) {
idx = (bufptr - buf->buffer) / SCSI_LOG_BUFSIZE;
ret = test_and_clear_bit(idx, &buf->map);
WARN_ON(!ret);
}
preempt_enable();
}
int sdev_prefix_printk(const char *level, const struct scsi_device *sdev,
const char *name, const char *fmt, ...)
{
va_list args;
char *logbuf;
size_t off = 0, logbuf_len;
int ret;
if (!sdev)
return 0;
logbuf = scsi_log_reserve_buffer(&logbuf_len);
if (!logbuf)
return 0;
if (name)
off += scnprintf(logbuf + off, logbuf_len - off,
"[%s] ", name);
va_start(args, fmt);
off += vscnprintf(logbuf + off, logbuf_len - off, fmt, args);
va_end(args);
ret = dev_printk(level, &sdev->sdev_gendev, "%s", logbuf);
scsi_log_release_buffer(logbuf);
return ret;
}
EXPORT_SYMBOL(sdev_prefix_printk);
int scmd_printk(const char *level, const struct scsi_cmnd *scmd,
const char *fmt, ...)
{
struct gendisk *disk = scmd->request->rq_disk;
va_list args;
char *logbuf;
size_t off = 0, logbuf_len;
int ret;
if (!scmd || !scmd->cmnd)
return 0;
logbuf = scsi_log_reserve_buffer(&logbuf_len);
if (!logbuf)
return 0;
if (disk)
off += scnprintf(logbuf + off, logbuf_len - off,
"[%s] ", disk->disk_name);
va_start(args, fmt);
off += vscnprintf(logbuf + off, logbuf_len - off, fmt, args);
va_end(args);
ret = dev_printk(level, &scmd->device->sdev_gendev, "%s", logbuf);
scsi_log_release_buffer(logbuf);
return ret;
}
EXPORT_SYMBOL(scmd_printk);
......@@ -230,9 +230,6 @@ struct scsi_dh_data {
#define transport_class_to_sdev(class_dev) \
to_scsi_device(class_dev->parent)
#define sdev_printk(prefix, sdev, fmt, a...) \
dev_printk(prefix, &(sdev)->sdev_gendev, fmt, ##a)
#define sdev_dbg(sdev, fmt, a...) \
dev_dbg(&(sdev)->sdev_gendev, fmt, ##a)
......@@ -240,16 +237,14 @@ struct scsi_dh_data {
* like scmd_printk, but the device name is passed in
* as a string pointer
*/
#define sdev_prefix_printk(l, sdev, p, fmt, a...) \
(p) ? \
sdev_printk(l, sdev, "[%s] " fmt, p, ##a) : \
sdev_printk(l, sdev, fmt, ##a)
#define scmd_printk(prefix, scmd, fmt, a...) \
(scmd)->request->rq_disk ? \
sdev_printk(prefix, (scmd)->device, "[%s] " fmt, \
(scmd)->request->rq_disk->disk_name, ##a) : \
sdev_printk(prefix, (scmd)->device, fmt, ##a)
extern int sdev_prefix_printk(const char *, const struct scsi_device *,
const char *, const char *, ...);
#define sdev_printk(l, sdev, fmt, a...) \
sdev_prefix_printk(l, sdev, NULL, fmt, ##a)
extern int scmd_printk(const char *, const struct scsi_cmnd *,
const char *, ...);
#define scmd_dbg(scmd, fmt, a...) \
do { \
......
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