[PATCH AUTOSEL 4.19 48/50] scsi: core: Reduce memory required for SCSI logging

Sasha Levin
2019-09-24T16:50:36Z

From: Bart Van Assche <bvanassche@acm.org>

[ Upstream commit dccc96abfb21dc19d69e707c38c8ba439bba7160 ]

The data structure used for log messages is so large that it can cause a
boot failure. Since allocations from that data structure can fail anyway,
use kmalloc() / kfree() instead of that data structure.

See also https://bugzilla.kernel.org/show_bug.cgi?id=204119.
See also commit ded85c193a39 ("scsi: Implement per-cpu logging buffer") # v4.0.

Reported-by: Jan Palus <jpalus@fastmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Jan Palus <jpalus@fastmail.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/scsi/scsi_logging.c | 48 +++----------------------------------
include/scsi/scsi_dbg.h | 2 --
2 files changed, 3 insertions(+), 47 deletions(-)

diff --git a/drivers/scsi/scsi_logging.c b/drivers/scsi/scsi_logging.c
index bd70339c1242e..03d9855a6afd7 100644
--- a/drivers/scsi/scsi_logging.c
+++ b/drivers/scsi/scsi_logging.c
@@ -16,57 +16,15 @@
#include <scsi/scsi_eh.h>
#include <scsi/scsi_dbg.h>

-#define SCSI_LOG_SPOOLSIZE 4096
-
-#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;
+ *len = 128;
+ return kmalloc(*len, GFP_ATOMIC);
}

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();
+ kfree(bufptr);
}

static inline const char *scmd_name(const struct scsi_cmnd *scmd)
diff --git a/include/scsi/scsi_dbg.h b/include/scsi/scsi_dbg.h
index e03bd9d41fa8f..7b196d2346264 100644
--- a/include/scsi/scsi_dbg.h
+++ b/include/scsi/scsi_dbg.h
@@ -6,8 +6,6 @@ struct scsi_cmnd;
struct scsi_device;
struct scsi_sense_hdr;

-#define SCSI_LOG_BUFSIZE 128
-
extern void scsi_print_command(struct scsi_cmnd *);
extern size_t __scsi_format_command(char *, size_t,
const unsigned char *, size_t);
--
2.20.1