Merge branch 'rework/prb-fixes' into for-linus

Author: pmladek

kernel/printk/printk_ringbuffer.c

@@ -14,7 +14,7 @@
  *
  * Data Structure
  * --------------
- * The printk_ringbuffer is made up of 3 internal ringbuffers:
+ * The printk_ringbuffer is made up of 2 internal ringbuffers:
  *
  *   desc_ring
  *     A ring of descriptors and their meta data (such as sequence number,
@@ -224,7 +224,7 @@
  *
  *	prb_rec_init_rd(&r, &info, &text_buf[0], sizeof(text_buf));
  *
- *	prb_for_each_record(0, &test_rb, &seq, &r) {
+ *	prb_for_each_record(0, &test_rb, seq, &r) {
  *		if (info.seq != seq)
  *			pr_warn("lost %llu records\n", info.seq - seq);
  *
@@ -1302,23 +1302,26 @@ static const char *get_data(struct prb_data_ring *data_ring,
 		return NULL;
 	}
 
-	/* Sanity check. Data-less blocks were handled earlier. */
-	if (WARN_ON_ONCE(!data_check_size(data_ring, *data_size) || !*data_size))
-		return NULL;
-
 	/* A valid data block will always be aligned to the ID size. */
 	if (WARN_ON_ONCE(blk_lpos->begin != ALIGN(blk_lpos->begin, sizeof(db->id))) ||
 	    WARN_ON_ONCE(blk_lpos->next != ALIGN(blk_lpos->next, sizeof(db->id)))) {
 		return NULL;
 	}
 
-	/* A valid data block will always have at least an ID. */
-	if (WARN_ON_ONCE(*data_size < sizeof(db->id)))
+	/*
+	 * A regular data block will always have an ID and at least
+	 * 1 byte of data. Data-less blocks were handled earlier.
+	 */
+	if (WARN_ON_ONCE(*data_size <= sizeof(db->id)))
 		return NULL;
 
 	/* Subtract block ID space from size to reflect data size. */
 	*data_size -= sizeof(db->id);
 
+	/* Sanity check the max size of the regular data block. */
+	if (WARN_ON_ONCE(!data_check_size(data_ring, *data_size)))
+		return NULL;
+
 	return &db->data[0];
 }
 
@@ -1365,7 +1368,7 @@ static struct prb_desc *desc_reopen_last(struct prb_desc_ring *desc_ring,
 	 *
 	 * WMB from _prb_commit:A to _prb_commit:B
 	 *    matching
-	 * MB If desc_reopen_last:A to prb_reserve_in_last:A
+	 * MB from desc_reopen_last:A to prb_reserve_in_last:A
 	 */
 	if (!atomic_long_try_cmpxchg(&d->state_var, &prev_state_val,
 			DESC_SV(id, desc_reserved))) { /* LMM(desc_reopen_last:A) */
@@ -1770,9 +1773,9 @@ static void _prb_commit(struct prb_reserved_entry *e, unsigned long state_val)
 	 *
 	 *    Relies on:
 	 *
-	 *    MB _prb_commit:B to prb_commit:A
+	 *    MB from _prb_commit:B to prb_commit:A
 	 *       matching
-	 *    MB desc_reserve:D to desc_make_final:A
+	 *    MB from desc_reserve:D to desc_make_final:A
 	 */
 	if (!atomic_long_try_cmpxchg(&d->state_var, &prev_state_val,
 			DESC_SV(e->id, state_val))) { /* LMM(_prb_commit:B) */
@@ -2035,7 +2038,7 @@ u64 prb_first_seq(struct printk_ringbuffer *rb)
 		 *
 		 * MB from desc_push_tail:B to desc_reserve:F
 		 *    matching
-		 * RMB prb_first_seq:B to prb_first_seq:A
+		 * RMB from prb_first_seq:B to prb_first_seq:A
 		 */
 		smp_rmb(); /* LMM(prb_first_seq:C) */
 	}

kernel/printk/printk_ringbuffer.h

@@ -127,7 +127,7 @@ enum desc_state {
 };
 
 #define _DATA_SIZE(sz_bits)	(1UL << (sz_bits))
-#define _DESCS_COUNT(ct_bits)	(1U << (ct_bits))
+#define _DESCS_COUNT(ct_bits)	(1UL << (ct_bits))
 #define DESC_SV_BITS		BITS_PER_LONG
 #define DESC_FLAGS_SHIFT	(DESC_SV_BITS - 2)
 #define DESC_FLAGS_MASK		(3UL << DESC_FLAGS_SHIFT)
@@ -388,7 +388,7 @@ for ((s) = from; prb_read_valid(rb, s, r); (s) = (r)->info->seq + 1)
  *
  * This is a macro for conveniently iterating over a ringbuffer.
  * Note that @s may not be the sequence number of the record on each
- * iteration. For the sequence number, @r->info->seq should be checked.
+ * iteration. For the sequence number, @i->seq should be checked.
  *
  * Context: Any context.
  */