releases/4.14.125/pstore-remove-needless-lock-during-console-writes.patch

   1 From b77fa617a2ff4d6beccad3d3d4b3a1f2d10368aa Mon Sep 17 00:00:00 2001
   2 From: Kees Cook <keescook@chromium.org>
   3 Date: Thu, 1 Nov 2018 14:08:07 -0700
   4 Subject: pstore: Remove needless lock during console writes
   5
   6 From: Kees Cook <keescook@chromium.org>
   7
   8 commit b77fa617a2ff4d6beccad3d3d4b3a1f2d10368aa upstream.
   9
  10 Since the console writer does not use the preallocated crash dump buffer
  11 any more, there is no reason to perform locking around it.
  12
  13 Fixes: 70ad35db3321 ("pstore: Convert console write to use ->write_buf")
  14 Signed-off-by: Kees Cook <keescook@chromium.org>
  15 Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
  16 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  17
  18 ---
  19  fs/pstore/platform.c |   29 ++++++-----------------------
  20  1 file changed, 6 insertions(+), 23 deletions(-)
  21
  22 --- a/fs/pstore/platform.c
  23 +++ b/fs/pstore/platform.c
  24 @@ -597,31 +597,14 @@ static void pstore_unregister_kmsg(void)
  25  #ifdef CONFIG_PSTORE_CONSOLE
  26  static void pstore_console_write(struct console *con, const char *s, unsigned c)
  27  {
  28 -       const char *e = s + c;
  29 +       struct pstore_record record;
  30
  31 -       while (s < e) {
  32 -               struct pstore_record record;
  33 -               unsigned long flags;
  34 +       pstore_record_init(&record, psinfo);
  35 +       record.type = PSTORE_TYPE_CONSOLE;
  36
  37 -               pstore_record_init(&record, psinfo);
  38 -               record.type = PSTORE_TYPE_CONSOLE;
  39 -
  40 -               if (c > psinfo->bufsize)
  41 -                       c = psinfo->bufsize;
  42 -
  43 -               if (oops_in_progress) {
  44 -                       if (!spin_trylock_irqsave(&psinfo->buf_lock, flags))
  45 -                               break;
  46 -               } else {
  47 -                       spin_lock_irqsave(&psinfo->buf_lock, flags);
  48 -               }
  49 -               record.buf = (char *)s;
  50 -               record.size = c;
  51 -               psinfo->write(&record);
  52 -               spin_unlock_irqrestore(&psinfo->buf_lock, flags);
  53 -               s += c;
  54 -               c = e - s;
  55 -       }
  56 +       record.buf = (char *)s;
  57 +       record.size = c;
  58 +       psinfo->write(&record);
  59  }
  60
  61  static struct console pstore_console = {