releases/4.19.50/pstore-remove-needless-lock-during-console-writes.patch

From b77fa617a2ff4d6beccad3d3d4b3a1f2d10368aa Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Thu, 1 Nov 2018 14:08:07 -0700
Subject: pstore: Remove needless lock during console writes

From: Kees Cook <keescook@chromium.org>

commit b77fa617a2ff4d6beccad3d3d4b3a1f2d10368aa upstream.

Since the console writer does not use the preallocated crash dump buffer
any more, there is no reason to perform locking around it.

Fixes: 70ad35db3321 ("pstore: Convert console write to use ->write_buf")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/pstore/platform.c |   29 ++++++-----------------------
 1 file changed, 6 insertions(+), 23 deletions(-)

--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -476,31 +476,14 @@ static void pstore_unregister_kmsg(void)
 #ifdef CONFIG_PSTORE_CONSOLE
 static void pstore_console_write(struct console *con, const char *s, unsigned c)
 {
-	const char *e = s + c;
+	struct pstore_record record;
 
-	while (s < e) {
-		struct pstore_record record;
-		unsigned long flags;
+	pstore_record_init(&record, psinfo);
+	record.type = PSTORE_TYPE_CONSOLE;
 
-		pstore_record_init(&record, psinfo);
-		record.type = PSTORE_TYPE_CONSOLE;
-
-		if (c > psinfo->bufsize)
-			c = psinfo->bufsize;
-
-		if (oops_in_progress) {
-			if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
-				break;
-		} else {
-			spin_lock_irqsave(&psinfo->buf_lock, flags);
-		}
-		record.buf = (char *)s;
-		record.size = c;
-		psinfo->write(&record);
-		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
-		s += c;
-		c = e - s;
-	}
+	record.buf = (char *)s;
+	record.size = c;
+	psinfo->write(&record);
 }
 
 static struct console pstore_console = {