rt-patches/0045-mm-scatterlist-Do-not-disable-irqs-on-RT.patch

   1 From c869201a074134780c5ebd12f6b23f1cf2959ece Mon Sep 17 00:00:00 2001
   2 From: Thomas Gleixner <tglx@linutronix.de>
   3 Date: Fri, 3 Jul 2009 08:44:34 -0500
   4 Subject: [PATCH 045/365] mm/scatterlist: Do not disable irqs on RT
   5
   6 The local_irq_save() is not only used to get things done "fast" but
   7 also to ensure that in case of SG_MITER_ATOMIC we are in "atomic"
   8 context for kmap_atomic(). For -RT it is enough to keep pagefault
   9 disabled (which is currently handled by kmap_atomic()).
  10
  11 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  12 ---
  13  lib/scatterlist.c | 6 +++---
  14  1 file changed, 3 insertions(+), 3 deletions(-)
  15
  16 diff --git a/lib/scatterlist.c b/lib/scatterlist.c
  17 index bafa993..ebe3b7e 100644
  18 --- a/lib/scatterlist.c
  19 +++ b/lib/scatterlist.c
  20 @@ -620,7 +620,7 @@ void sg_miter_stop(struct sg_mapping_iter *miter)
  21                         flush_kernel_dcache_page(miter->page);
  22
  23                 if (miter->__flags & SG_MITER_ATOMIC) {
  24 -                       WARN_ON_ONCE(preemptible());
  25 +                       WARN_ON_ONCE(!pagefault_disabled());
  26                         kunmap_atomic(miter->addr);
  27                 } else
  28                         kunmap(miter->page);
  29 @@ -664,7 +664,7 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
  30         if (!sg_miter_skip(&miter, skip))
  31                 return false;
  32
  33 -       local_irq_save(flags);
  34 +       local_irq_save_nort(flags);
  35
  36         while (sg_miter_next(&miter) && offset < buflen) {
  37                 unsigned int len;
  38 @@ -681,7 +681,7 @@ size_t sg_copy_buffer(struct scatterlist *sgl, unsigned int nents, void *buf,
  39
  40         sg_miter_stop(&miter);
  41
  42 -       local_irq_restore(flags);
  43 +       local_irq_restore_nort(flags);
  44         return offset;
  45  }
  46  EXPORT_SYMBOL(sg_copy_buffer);
  47 --
  48 2.7.4
  49