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-rw-r--r--kernel/printk/printk.c30
1 files changed, 23 insertions, 7 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 99b7a2d..8fbbab1 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -297,12 +297,20 @@ static u32 log_next(u32 idx)
return idx + msg->len;
}
-/* check whether there is enough free space for the given message */
-static int logbuf_has_space(u32 msg_size)
+/*
+ * Check whether there is enough free space for the given message.
+ *
+ * The same values of first_idx and next_idx mean that the buffer
+ * is either empty or full.
+ *
+ * If the buffer is empty, we must respect the position of the indexes.
+ * They cannot be reset to the beginning of the buffer.
+ */
+static int logbuf_has_space(u32 msg_size, bool empty)
{
u32 free;
- if (log_next_idx > log_first_idx)
+ if (log_next_idx > log_first_idx || empty)
free = max(log_buf_len - log_next_idx, log_first_idx);
else
free = log_first_idx - log_next_idx;
@@ -314,15 +322,21 @@ static int logbuf_has_space(u32 msg_size)
return free >= msg_size + sizeof(struct printk_log);
}
-static void log_make_free_space(u32 msg_size)
+static int log_make_free_space(u32 msg_size)
{
while (log_first_seq < log_next_seq) {
- if (logbuf_has_space(msg_size))
- return;
+ if (logbuf_has_space(msg_size, false))
+ return 0;
/* drop old messages until we have enough continuous space */
log_first_idx = log_next(log_first_idx);
log_first_seq++;
}
+
+ /* sequence numbers are equal, so the log buffer is empty */
+ if (logbuf_has_space(msg_size, true))
+ return 0;
+
+ return -ENOMEM;
}
/* insert record into the buffer, discard old ones, update heads */
@@ -339,7 +353,9 @@ static void log_store(int facility, int level,
pad_len = (-size) & (LOG_ALIGN - 1);
size += pad_len;
- log_make_free_space(size);
+ /* if message does not fit empty log buffer, ignore it */
+ if (log_make_free_space(size))
+ return;
if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) {
/*
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