x86, UV: Remove BAU check for stay-busy

Remove a faulty assumption that a long running BAU request has
encountered a hardware problem and will never finish.

Numalink congestion can make a request appear to have
encountered such a problem, but it is not safe to cancel the
request.  If such a cancel is done but a reply is later received
we can miss a TLB shootdown.

We depend upon the max_bau_concurrent 'throttle' to prevent the
stay-busy case from happening.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
Cc: gregkh@suse.de
LKML-Reference: <E1OJvNy-0004ad-BV@eag09.americas.sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/include/asm/uv/uv_bau.h b/arch/x86/include/asm/uv/uv_bau.h
index 1c8f1e9..c19b870 100644 (file)
--- a/arch/x86/include/asm/uv/uv_bau.h
+++ b/arch/x86/include/asm/uv/uv_bau.h
@@ -402,7 +402,6 @@ struct bau_control {
        unsigned short uvhub_quiesce;
        short socket_acknowledge_count[DEST_Q_SIZE];
        cycles_t send_message;
-       spinlock_t masks_lock;
        spinlock_t uvhub_lock;
        spinlock_t queue_lock;
        /* tunables */

diff --git a/arch/x86/kernel/tlb_uv.c b/arch/x86/kernel/tlb_uv.c
index ab929e9..dc962b5 100644 (file)
--- a/arch/x86/kernel/tlb_uv.c
+++ b/arch/x86/kernel/tlb_uv.c
@@ -405,12 +405,10 @@ static int uv_wait_completion(struct bau_desc *bau_desc,
        unsigned long mmr;
        unsigned long mask;
        cycles_t ttime;
-       cycles_t timeout_time;
        struct ptc_stats *stat = bcp->statp;
        struct bau_control *hmaster;
 
        hmaster = bcp->uvhub_master;
-       timeout_time = get_cycles() + bcp->timeout_interval;
 
        /* spin on the status MMR, waiting for it to go idle */
        while ((descriptor_status = (((unsigned long)
@@ -450,26 +448,6 @@ static int uv_wait_completion(struct bau_desc *bau_desc,
                         * descriptor_status is still BUSY
                         */
                        cpu_relax();
-                       relaxes++;
-                       if (relaxes >= 10000) {
-                               relaxes = 0;
-                               if (get_cycles() > timeout_time) {
-                                       quiesce_local_uvhub(hmaster);
-
-                                       /* single-thread the register change */
-                                       spin_lock(&hmaster->masks_lock);
-                                       mmr = uv_read_local_mmr(mmr_offset);
-                                       mask = 0UL;
-                                       mask |= (3UL < right_shift);
-                                       mask = ~mask;
-                                       mmr &= mask;
-                                       uv_write_local_mmr(mmr_offset, mmr);
-                                       spin_unlock(&hmaster->masks_lock);
-                                       end_uvhub_quiesce(hmaster);
-                                       stat->s_busy++;
-                                       return FLUSH_GIVEUP;
-                               }
-                       }
                }
        }
        bcp->conseccompletes++;
@@ -1580,7 +1558,6 @@ static void uv_init_per_cpu(int nuvhubs)
        for_each_present_cpu(cpu) {
                bcp = &per_cpu(bau_control, cpu);
                memset(bcp, 0, sizeof(struct bau_control));
-               spin_lock_init(&bcp->masks_lock);
                pnode = uv_cpu_hub_info(cpu)->pnode;
                uvhub = uv_cpu_hub_info(cpu)->numa_blade_id;
                uvhub_mask |= (1 << uvhub);