rt-patches/0169-net-Use-cpu_chill-instead-of-cpu_relax.patch

   1 From 506b107258faad9ea2168f543fed81666caa68d2 Mon Sep 17 00:00:00 2001
   2 From: Thomas Gleixner <tglx@linutronix.de>
   3 Date: Wed, 7 Mar 2012 21:10:04 +0100
   4 Subject: [PATCH 169/366] net: Use cpu_chill() instead of cpu_relax()
   5
   6 Retry loops on RT might loop forever when the modifying side was
   7 preempted. Use cpu_chill() instead of cpu_relax() to let the system
   8 make progress.
   9
  10 Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
  11 ---
  12  net/packet/af_packet.c | 5 +++--
  13  net/rds/ib_rdma.c      | 3 ++-
  14  2 files changed, 5 insertions(+), 3 deletions(-)
  15
  16 diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
  17 index c148581..759d6ed 100644
  18 --- a/net/packet/af_packet.c
  19 +++ b/net/packet/af_packet.c
  20 @@ -63,6 +63,7 @@
  21  #include <linux/if_packet.h>
  22  #include <linux/wireless.h>
  23  #include <linux/kernel.h>
  24 +#include <linux/delay.h>
  25  #include <linux/kmod.h>
  26  #include <linux/slab.h>
  27  #include <linux/vmalloc.h>
  28 @@ -694,7 +695,7 @@ static void prb_retire_rx_blk_timer_expired(unsigned long data)
  29         if (BLOCK_NUM_PKTS(pbd)) {
  30                 while (atomic_read(&pkc->blk_fill_in_prog)) {
  31                         /* Waiting for skb_copy_bits to finish... */
  32 -                       cpu_relax();
  33 +                       cpu_chill();
  34                 }
  35         }
  36
  37 @@ -956,7 +957,7 @@ static void prb_retire_current_block(struct tpacket_kbdq_core *pkc,
  38                 if (!(status & TP_STATUS_BLK_TMO)) {
  39                         while (atomic_read(&pkc->blk_fill_in_prog)) {
  40                                 /* Waiting for skb_copy_bits to finish... */
  41 -                               cpu_relax();
  42 +                               cpu_chill();
  43                         }
  44                 }
  45                 prb_close_block(pkc, pbd, po, status);
  46 diff --git a/net/rds/ib_rdma.c b/net/rds/ib_rdma.c
  47 index a234074..19123a9 100644
  48 --- a/net/rds/ib_rdma.c
  49 +++ b/net/rds/ib_rdma.c
  50 @@ -34,6 +34,7 @@
  51  #include <linux/slab.h>
  52  #include <linux/rculist.h>
  53  #include <linux/llist.h>
  54 +#include <linux/delay.h>
  55
  56  #include "rds.h"
  57  #include "ib.h"
  58 @@ -313,7 +314,7 @@ static inline void wait_clean_list_grace(void)
  59         for_each_online_cpu(cpu) {
  60                 flag = &per_cpu(clean_list_grace, cpu);
  61                 while (test_bit(CLEAN_LIST_BUSY_BIT, flag))
  62 -                       cpu_relax();
  63 +                       cpu_chill();
  64         }
  65  }
  66
  67 --
  68 1.9.1
  69