linux-kernel - [RFC/PATCH 2/2] pstore: Convert console write to use ->write

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Date:   Wed, 19 Oct 2016 10:23:41 +0900
From:   Namhyung Kim <namhyung@...nel.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Anton Vorontsov <anton@...msg.org>,
        Colin Cross <ccross@...roid.com>,
        Tony Luck <tony.luck@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Stefan Hajnoczi <stefanha@...hat.com>
Subject: [RFC/PATCH 2/2] pstore: Convert console write to use ->write_buf

Maybe I'm missing something, but I don't know why it needs to copy the
input buffer to psinfo->buf and then write.  Instead we can write the
input buffer directly.  The only implementation that supports console
message (i.e. ramoops) already does it for ftrace messages.

For the upcoming virtio backend driver, it needs to protect psinfo->buf
overwritten from console messages.  If it could use ->write_buf method
instead of ->write, the problem will be solved easily.

Cc: Stefan Hajnoczi <stefanha@...hat.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 fs/pstore/platform.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index 14984d902a99..960d66251bab 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -584,8 +584,8 @@ static void pstore_console_write(struct console *con, const char *s, unsigned c)
 		} else {
 			spin_lock_irqsave(&psinfo->buf_lock, flags);
 		}
-		memcpy(psinfo->buf, s, c);
-		psinfo->write(PSTORE_TYPE_CONSOLE, 0, &id, 0, 0, 0, c, psinfo);
+		psinfo->write_buf(PSTORE_TYPE_CONSOLE, 0, &id, 0,
+				  s, 0, c, psinfo);
 		spin_unlock_irqrestore(&psinfo->buf_lock, flags);
 		s += c;
 		c = e - s;
-- 
2.9.3