gru: add comments raised in previous code reviews

Add comments from previous code reviews.  The comments help explain some
of the more esoteric aspects of the driver.

Move a free() to the other side of an unlock.

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 679e017..2605edf 100644 (file)
--- a/drivers/misc/sgi-gru/grufault.c
+++ b/drivers/misc/sgi-gru/grufault.c
@@ -733,6 +733,11 @@ long gru_get_gseg_statistics(unsigned long arg)
        if (copy_from_user(&req, (void __user *)arg, sizeof(req)))
                return -EFAULT;
 
+       /*
+        * The library creates arrays of contexts for threaded programs.
+        * If no gts exists in the array, the context has never been used & all
+        * statistics are implicitly 0.
+        */
        gts = gru_find_lock_gts(req.gseg);
        if (gts) {
                memcpy(&req.stats, &gts->ustats, sizeof(gts->ustats));

diff --git a/drivers/misc/sgi-gru/grukservices.c b/drivers/misc/sgi-gru/grukservices.c
index d2b149f..306855c 100644 (file)
--- a/drivers/misc/sgi-gru/grukservices.c
+++ b/drivers/misc/sgi-gru/grukservices.c
@@ -200,13 +200,15 @@ static int gru_free_kernel_contexts(void)
                bs = gru_base[bid];
                if (!bs)
                        continue;
+
+               /* Ignore busy contexts. Don't want to block here.  */
                if (down_write_trylock(&bs->bs_kgts_sema)) {
                        kgts = bs->bs_kgts;
                        if (kgts && kgts->ts_gru)
                                gru_unload_context(kgts, 0);
-                       kfree(kgts);
                        bs->bs_kgts = NULL;
                        up_write(&bs->bs_kgts_sema);
+                       kfree(kgts);
                } else {
                        ret++;
                }