Merge branch 'pci-for-jesse' of git://git.kernel.org/pub/scm/linux/kernel/git/tip...

[~andy/linux] / fs / xfs / support / ktrace.c

diff --git a/fs/xfs/support/ktrace.c b/fs/xfs/support/ktrace.c
index 4e0444c0aca6958f91d15e18908acb364c27fd9f..a34ef05489b1c323369c7b22cf40400febaa28dd 100644 (file)
--- a/fs/xfs/support/ktrace.c
+++ b/fs/xfs/support/ktrace.c
@@ -24,7 +24,7 @@ static int          ktrace_zentries;
 void __init
 ktrace_init(int zentries)
 {
-       ktrace_zentries = zentries;
+       ktrace_zentries = roundup_pow_of_two(zentries);
 
        ktrace_hdr_zone = kmem_zone_init(sizeof(ktrace_t),
                                        "ktrace_hdr");
@@ -47,13 +47,16 @@ ktrace_uninit(void)
  * ktrace_alloc()
  *
  * Allocate a ktrace header and enough buffering for the given
- * number of entries.
+ * number of entries. Round the number of entries up to a
+ * power of 2 so we can do fast masking to get the index from
+ * the atomic index counter.
  */
 ktrace_t *
 ktrace_alloc(int nentries, unsigned int __nocast sleep)
 {
        ktrace_t        *ktp;
        ktrace_entry_t  *ktep;
+       int             entries;
 
        ktp = (ktrace_t*)kmem_zone_alloc(ktrace_hdr_zone, sleep);
 
@@ -70,11 +73,12 @@ ktrace_alloc(int nentries, unsigned int __nocast sleep)
        /*
         * Special treatment for buffers with the ktrace_zentries entries
         */
-       if (nentries == ktrace_zentries) {
+       entries = roundup_pow_of_two(nentries);
+       if (entries == ktrace_zentries) {
                ktep = (ktrace_entry_t*)kmem_zone_zalloc(ktrace_ent_zone,
                                                            sleep);
        } else {
-               ktep = (ktrace_entry_t*)kmem_zalloc((nentries * sizeof(*ktep)),
+               ktep = (ktrace_entry_t*)kmem_zalloc((entries * sizeof(*ktep)),
                                                            sleep | KM_LARGE);
        }
 
@@ -85,13 +89,15 @@ ktrace_alloc(int nentries, unsigned int __nocast sleep)
                if (sleep & KM_SLEEP)
                        panic("ktrace_alloc: NULL memory on KM_SLEEP request!");
 
-               kmem_free(ktp, sizeof(*ktp));
+               kmem_free(ktp);
 
                return NULL;
        }
 
        ktp->kt_entries  = ktep;
-       ktp->kt_nentries = nentries;
+       ktp->kt_nentries = entries;
+       ASSERT(is_power_of_2(entries));
+       ktp->kt_index_mask = entries - 1;
        atomic_set(&ktp->kt_index, 0);
        ktp->kt_rollover = 0;
        return ktp;
@@ -120,7 +126,7 @@ ktrace_free(ktrace_t *ktp)
        } else {
                entries_size = (int)(ktp->kt_nentries * sizeof(ktrace_entry_t));
 
-               kmem_free(ktp->kt_entries, entries_size);
+               kmem_free(ktp->kt_entries);
        }
 
        kmem_zone_free(ktrace_hdr_zone, ktp);
@@ -160,7 +166,7 @@ ktrace_enter(
         * Grab an entry by pushing the index up to the next one.
         */
        index = atomic_add_return(1, &ktp->kt_index);
-       index = (index - 1) % ktp->kt_nentries;
+       index = (index - 1) & ktp->kt_index_mask;
        if (!ktp->kt_rollover && index == ktp->kt_nentries - 1)
                ktp->kt_rollover = 1;
 
@@ -197,7 +203,7 @@ ktrace_nentries(
        if (ktp == NULL)
                return 0;
 
-       index = atomic_read(&ktp->kt_index) % ktp->kt_nentries;
+       index = atomic_read(&ktp->kt_index) & ktp->kt_index_mask;
        return (ktp->kt_rollover ? ktp->kt_nentries : index);
 }
 
@@ -223,7 +229,7 @@ ktrace_first(ktrace_t   *ktp, ktrace_snap_t     *ktsp)
        int             nentries;
 
        if (ktp->kt_rollover)
-               index = atomic_read(&ktp->kt_index) % ktp->kt_nentries;
+               index = atomic_read(&ktp->kt_index) & ktp->kt_index_mask;
        else
                index = 0;