linux-kernel - [PATCH 7/8] pstore: Remove needless lock during console writes

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Message-Id: <20181101235200.28584-8-keescook@chromium.org>
Date:   Thu,  1 Nov 2018 16:51:59 -0700
From:   Kees Cook <keescook@...omium.org>
To:     linux-kernel@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>
Subject: [PATCH 7/8] pstore: Remove needless lock during console writes

Since commit 70ad35db3321 ("pstore: Convert console write to use
->write_buf"), the console writer does not use the preallocated crash
dump buffer any more, so there is no reason to perform locking around it.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 fs/pstore/platform.c | 29 ++++++-----------------------
 1 file changed, 6 insertions(+), 23 deletions(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index a956c7bc3f67..32340e7dd6a5 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -461,31 +461,14 @@ 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;
-
-		if (c > psinfo->bufsize)
-			c = psinfo->bufsize;
+	pstore_record_init(&record, psinfo);
+	record.type = PSTORE_TYPE_CONSOLE;
 
-		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 = {
-- 
2.17.1