From ded85c193a391a84076d5c6a7a5668fe164a490e Mon Sep 17 00:00:00 2001 From: Hannes Reinecke Date: Thu, 8 Jan 2015 07:43:42 +0100 Subject: 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: Robert Elliott Reviewed-by: Robert Elliott Signed-off-by: Hannes Reinecke Signed-off-by: Christoph Hellwig diff --git a/drivers/scsi/Makefile b/drivers/scsi/Makefile index 58158f1..447c2d2 100644 --- a/drivers/scsi/Makefile +++ b/drivers/scsi/Makefile @@ -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 diff --git a/drivers/scsi/scsi_logging.c b/drivers/scsi/scsi_logging.c new file mode 100644 index 0000000..09d65de --- /dev/null +++ b/drivers/scsi/scsi_logging.c @@ -0,0 +1,124 @@ +/* + * scsi_logging.c + * + * Copyright (C) 2014 SUSE Linux Products GmbH + * Copyright (C) 2014 Hannes Reinecke + * + * This file is released under the GPLv2 + */ + +#include +#include + +#include +#include +#include +#include + +#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); diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h index 3a4edd1..d1aad4d 100644 --- a/include/scsi/scsi_device.h +++ b/include/scsi/scsi_device.h @@ -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 { \ -- cgit v0.10.2