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ded85c193a
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 <elliott@hp.com> Reviewed-by: Robert Elliott <elliott@hp.com> Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Christoph Hellwig <hch@lst.de>
125 lines
2.8 KiB
C
125 lines
2.8 KiB
C
/*
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* scsi_logging.c
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*
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* Copyright (C) 2014 SUSE Linux Products GmbH
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* Copyright (C) 2014 Hannes Reinecke <hare@suse.de>
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*
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* This file is released under the GPLv2
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*/
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#include <linux/kernel.h>
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#include <linux/atomic.h>
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#include <scsi/scsi.h>
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#include <scsi/scsi_cmnd.h>
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#include <scsi/scsi_device.h>
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#include <scsi/scsi_dbg.h>
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#define SCSI_LOG_SPOOLSIZE 4096
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#define SCSI_LOG_BUFSIZE 128
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#if (SCSI_LOG_SPOOLSIZE / SCSI_LOG_BUFSIZE) > BITS_PER_LONG
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#warning SCSI logging bitmask too large
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#endif
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struct scsi_log_buf {
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char buffer[SCSI_LOG_SPOOLSIZE];
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unsigned long map;
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};
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static DEFINE_PER_CPU(struct scsi_log_buf, scsi_format_log);
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static char *scsi_log_reserve_buffer(size_t *len)
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{
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struct scsi_log_buf *buf;
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unsigned long map_bits = sizeof(buf->buffer) / SCSI_LOG_BUFSIZE;
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unsigned long idx = 0;
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preempt_disable();
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buf = this_cpu_ptr(&scsi_format_log);
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idx = find_first_zero_bit(&buf->map, map_bits);
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if (likely(idx < map_bits)) {
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while (test_and_set_bit(idx, &buf->map)) {
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idx = find_next_zero_bit(&buf->map, map_bits, idx);
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if (idx >= map_bits)
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break;
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}
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}
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if (WARN_ON(idx >= map_bits)) {
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preempt_enable();
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return NULL;
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}
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*len = SCSI_LOG_BUFSIZE;
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return buf->buffer + idx * SCSI_LOG_BUFSIZE;
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}
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static void scsi_log_release_buffer(char *bufptr)
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{
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struct scsi_log_buf *buf;
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unsigned long idx;
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int ret;
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buf = this_cpu_ptr(&scsi_format_log);
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if (bufptr >= buf->buffer &&
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bufptr < buf->buffer + SCSI_LOG_SPOOLSIZE) {
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idx = (bufptr - buf->buffer) / SCSI_LOG_BUFSIZE;
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ret = test_and_clear_bit(idx, &buf->map);
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WARN_ON(!ret);
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}
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preempt_enable();
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}
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int sdev_prefix_printk(const char *level, const struct scsi_device *sdev,
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const char *name, const char *fmt, ...)
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{
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va_list args;
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char *logbuf;
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size_t off = 0, logbuf_len;
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int ret;
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if (!sdev)
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return 0;
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logbuf = scsi_log_reserve_buffer(&logbuf_len);
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if (!logbuf)
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return 0;
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if (name)
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off += scnprintf(logbuf + off, logbuf_len - off,
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"[%s] ", name);
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va_start(args, fmt);
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off += vscnprintf(logbuf + off, logbuf_len - off, fmt, args);
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va_end(args);
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ret = dev_printk(level, &sdev->sdev_gendev, "%s", logbuf);
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scsi_log_release_buffer(logbuf);
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return ret;
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}
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EXPORT_SYMBOL(sdev_prefix_printk);
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int scmd_printk(const char *level, const struct scsi_cmnd *scmd,
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const char *fmt, ...)
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{
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struct gendisk *disk = scmd->request->rq_disk;
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va_list args;
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char *logbuf;
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size_t off = 0, logbuf_len;
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int ret;
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if (!scmd || !scmd->cmnd)
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return 0;
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logbuf = scsi_log_reserve_buffer(&logbuf_len);
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if (!logbuf)
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return 0;
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if (disk)
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off += scnprintf(logbuf + off, logbuf_len - off,
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"[%s] ", disk->disk_name);
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va_start(args, fmt);
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off += vscnprintf(logbuf + off, logbuf_len - off, fmt, args);
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va_end(args);
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ret = dev_printk(level, &scmd->device->sdev_gendev, "%s", logbuf);
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scsi_log_release_buffer(logbuf);
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return ret;
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}
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EXPORT_SYMBOL(scmd_printk);
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