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    Subject[Patch 27/29] GRU - Fix GRU interrupt race at deallocate
    From: Jack Steiner <steiner@sgi.com>

    Fix a race where an interrupt could be received for a GRU context that
    has been deallocated.


    Signed-off-by: Jack Steiner <steiner@sgi.com>


    ---
    drivers/misc/sgi-gru/grufault.c | 24 +++++++++++++++++-------
    drivers/misc/sgi-gru/gruprocfs.c | 1 +
    drivers/misc/sgi-gru/grutables.h | 1 +
    3 files changed, 19 insertions(+), 7 deletions(-)

    Index: linux/drivers/misc/sgi-gru/grufault.c
    ===================================================================
    --- linux.orig/drivers/misc/sgi-gru/grufault.c 2009-11-20 09:32:38.000000000 -0600
    +++ linux/drivers/misc/sgi-gru/grufault.c 2009-11-20 09:32:38.000000000 -0600
    @@ -360,7 +360,8 @@ static void gru_preload_tlb(struct gru_s
    * < 0 = error code
    *
    */
    -static int gru_try_dropin(struct gru_thread_state *gts,
    +static int gru_try_dropin(struct gru_state *gru,
    + struct gru_thread_state *gts,
    struct gru_tlb_fault_handle *tfh,
    struct gru_instruction_bits *cbk)
    {
    @@ -432,7 +433,7 @@ static int gru_try_dropin(struct gru_thr
    }

    if (unlikely(cbe) && pageshift == PAGE_SHIFT) {
    - gru_preload_tlb(gts->ts_gru, gts, atomic, vaddr, asid, write, tlb_preload_count, tfh, cbe);
    + gru_preload_tlb(gru, gts, atomic, vaddr, asid, write, tlb_preload_count, tfh, cbe);
    gru_flush_cache_cbe(cbe);
    }

    @@ -442,7 +443,7 @@ static int gru_try_dropin(struct gru_thr
    gru_dbg(grudev,
    "%s: gid %d, gts 0x%p, tfh 0x%p, vaddr 0x%lx, asid 0x%x, indexway 0x%x,"
    " rw %d, ps %d, gpa 0x%lx\n",
    - atomic ? "atomic" : "non-atomic", gts->ts_gru->gs_gid, gts, tfh, vaddr, asid,
    + atomic ? "atomic" : "non-atomic", gru->gs_gid, gts, tfh, vaddr, asid,
    indexway, write, pageshift, gpa);
    STAT(tlb_dropin);
    return 0;
    @@ -528,6 +529,7 @@ static irqreturn_t gru_intr(int chiplet,
    struct gru_tlb_fault_map imap, dmap;
    struct gru_thread_state *gts;
    struct gru_tlb_fault_handle *tfh = NULL;
    + struct completion *cmp;
    int cbrnum, ctxnum;

    STAT(intr);
    @@ -547,9 +549,11 @@ static irqreturn_t gru_intr(int chiplet,

    for_each_cbr_in_tfm(cbrnum, dmap.fault_bits) {
    STAT(intr_cbr);
    - complete(gru->gs_blade->bs_async_wq);
    + cmp = gru->gs_blade->bs_async_wq;
    + if (cmp)
    + complete(cmp);
    gru_dbg(grudev, "gid %d, cbr_done %d, done %d\n",
    - gru->gs_gid, cbrnum, gru->gs_blade->bs_async_wq->done);
    + gru->gs_gid, cbrnum, cmp ? cmp->done : -1);
    }

    for_each_cbr_in_tfm(cbrnum, imap.fault_bits) {
    @@ -566,6 +570,12 @@ static irqreturn_t gru_intr(int chiplet,
    ctxnum = tfh->ctxnum;
    gts = gru->gs_gts[ctxnum];

    + /* Spurious interrupts can cause this. Ignore. */
    + if (!gts) {
    + STAT(intr_spurious);
    + continue;
    + }
    +
    /*
    * This is running in interrupt context. Trylock the mmap_sem.
    * If it fails, retry the fault in user context.
    @@ -573,7 +583,7 @@ static irqreturn_t gru_intr(int chiplet,
    if (!gts->ts_force_cch_reload &&
    down_read_trylock(&gts->ts_mm->mmap_sem)) {
    gts->ustats.fmm_tlbdropin++;
    - gru_try_dropin(gts, tfh, NULL);
    + gru_try_dropin(gru, gts, tfh, NULL);
    up_read(&gts->ts_mm->mmap_sem);
    } else {
    tfh_user_polling_mode(tfh);
    @@ -619,7 +629,7 @@ static int gru_user_dropin(struct gru_th
    wait_event(gms->ms_wait_queue,
    atomic_read(&gms->ms_range_active) == 0);
    prefetchw(tfh); /* Helps on hdw, required for emulator */
    - ret = gru_try_dropin(gts, tfh, cb);
    + ret = gru_try_dropin(gts->ts_gru, gts, tfh, cb);
    if (ret <= 0)
    return ret;
    STAT(call_os_wait_queue);
    Index: linux/drivers/misc/sgi-gru/gruprocfs.c
    ===================================================================
    --- linux.orig/drivers/misc/sgi-gru/gruprocfs.c 2009-11-20 09:32:35.000000000 -0600
    +++ linux/drivers/misc/sgi-gru/gruprocfs.c 2009-11-20 09:32:38.000000000 -0600
    @@ -66,6 +66,7 @@ static int statistics_show(struct seq_fi
    printstat(s, intr);
    printstat(s, intr_cbr);
    printstat(s, intr_tfh);
    + printstat(s, intr_spurious);
    printstat(s, intr_mm_lock_failed);
    printstat(s, call_os);
    printstat(s, call_os_wait_queue);
    Index: linux/drivers/misc/sgi-gru/grutables.h
    ===================================================================
    --- linux.orig/drivers/misc/sgi-gru/grutables.h 2009-11-20 09:32:35.000000000 -0600
    +++ linux/drivers/misc/sgi-gru/grutables.h 2009-11-20 09:32:38.000000000 -0600
    @@ -192,6 +192,7 @@ struct gru_stats_s {
    atomic_long_t intr;
    atomic_long_t intr_cbr;
    atomic_long_t intr_tfh;
    + atomic_long_t intr_spurious;
    atomic_long_t intr_mm_lock_failed;
    atomic_long_t call_os;
    atomic_long_t call_os_wait_queue;


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