scsi: core: Reduce memory required for SCSI logging

BugLink: https://bugs.launchpad.net/bugs/1848274
[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/drivers/scsi/scsi_logging.c b/drivers/scsi/scsi_logging.c
index bd70339c1242eb1f2515a7a947b007472823a3c8..03d9855a6afd71ef5893b37623dc27c39db1cdbc 100644 (file)
--- 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 04e0679767f633f3ba80c962299914ec7f727957..2b5dfae78272290d239ac1ed7a1661c57dc44827 100644 (file)
--- 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);