> -----Original Message-----
> From: Hannes Reinecke [mailto:h...@suse.de]
> Sent: Tuesday, 04 November, 2014 2:07 AM
...
> diff --git a/drivers/scsi/scsi_logging.c
> b/drivers/scsi/scsi_logging.c
...
> @@ -0,0 +1,119 @@
> +/*
> + * scsi_logging.c
> + *
> + * Copyright (C) 2014 SUSE Linux Products GmbH
> + * Copyright (C) 2014 Hannes Reinecke <h...@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
> +
> +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 = SCSI_LOG_SPOOLSIZE / SCSI_LOG_BUFSIZE;
> + unsigned long idx = 0;
> +
> + WARN_ON(map_bits > BITS_PER_LONG);
Since SCSI_LOG_SPOOLSIZE, SCSI_LOG_BUFSIZE, and BITS_PER_LONG
are constants, that can be a compile-time check.
> + preempt_disable();
> + buf = this_cpu_ptr(&scsi_format_log);
> + idx = find_first_zero_bit(&buf->map, map_bits);
If this fails to find a bit, it returns map_bits.
This could result in the next test_and_set_bit call
accessing an address that is outside the bounds of
buf->map.
A safety check seems prudent before the test_and_set_bit:
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;
> + }
scripts/checkpatch.pl -f doesn't like the {} on that.
> + }
> + 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 + SCSI_LOG_SPOOLSIZE) {
Should that also check that bufptr > buf->buffer?
> + 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_GPL(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 == NULL)
> + return 0;
!scmd->cmnd seems more common in neighboring code.
> +
> + 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_GPL(scmd_printk);
...
dev_printk is EXPORT_SYMBOL. The former macro versions of
sdev_printk and scmd_printk just called dev_printk, and not
being symbols, did not change that.
So, I think these function versions should use EXPORT_SYMBOL, so
the hated binary drivers can still call them.
---
Rob Elliott HP Server Storage
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