gru: fix GRU interrupt race at deallocate

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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c
index 929d607..6ff6dfb 100644 (file)
--- a/drivers/misc/sgi-gru/grufault.c
+++ b/drivers/misc/sgi-gru/grufault.c
@@ -360,7 +360,8 @@ static void gru_preload_tlb(struct gru_state *gru,
  *             < 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_thread_state *gts,
        }
 
        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_thread_state *gts,
        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, int blade)
        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, int blade)
 
        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, int blade)
                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, int blade)
                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_thread_state *gts,
                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);

diff --git a/drivers/misc/sgi-gru/gruprocfs.c b/drivers/misc/sgi-gru/gruprocfs.c
index 54a5a1c..7768b87 100644 (file)
--- a/drivers/misc/sgi-gru/gruprocfs.c
+++ b/drivers/misc/sgi-gru/gruprocfs.c
@@ -66,6 +66,7 @@ static int statistics_show(struct seq_file *s, void *p)
        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);

diff --git a/drivers/misc/sgi-gru/grutables.h b/drivers/misc/sgi-gru/grutables.h
index adaf691..54c3bb1 100644 (file)
--- a/drivers/misc/sgi-gru/grutables.h
+++ b/drivers/misc/sgi-gru/grutables.h
@@ -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;