Merge tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm

[platform/kernel/linux-rpi.git] / kernel / ucount.c

diff --git a/kernel/ucount.c b/kernel/ucount.c
index bb51849..eb03f3c 100644 (file)
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -284,6 +284,55 @@ bool dec_rlimit_ucounts(struct ucounts *ucounts, enum ucount_type type, long v)
        return (new == 0);
 }
 
+static void do_dec_rlimit_put_ucounts(struct ucounts *ucounts,
+                               struct ucounts *last, enum ucount_type type)
+{
+       struct ucounts *iter, *next;
+       for (iter = ucounts; iter != last; iter = next) {
+               long dec = atomic_long_add_return(-1, &iter->ucount[type]);
+               WARN_ON_ONCE(dec < 0);
+               next = iter->ns->ucounts;
+               if (dec == 0)
+                       put_ucounts(iter);
+       }
+}
+
+void dec_rlimit_put_ucounts(struct ucounts *ucounts, enum ucount_type type)
+{
+       do_dec_rlimit_put_ucounts(ucounts, NULL, type);
+}
+
+long inc_rlimit_get_ucounts(struct ucounts *ucounts, enum ucount_type type)
+{
+       /* Caller must hold a reference to ucounts */
+       struct ucounts *iter;
+       long dec, ret = 0;
+
+       for (iter = ucounts; iter; iter = iter->ns->ucounts) {
+               long max = READ_ONCE(iter->ns->ucount_max[type]);
+               long new = atomic_long_add_return(1, &iter->ucount[type]);
+               if (new < 0 || new > max)
+                       goto unwind;
+               if (iter == ucounts)
+                       ret = new;
+               /*
+                * Grab an extra ucount reference for the caller when
+                * the rlimit count was previously 0.
+                */
+               if (new != 1)
+                       continue;
+               if (!get_ucounts(iter))
+                       goto dec_unwind;
+       }
+       return ret;
+dec_unwind:
+       dec = atomic_long_add_return(-1, &iter->ucount[type]);
+       WARN_ON_ONCE(dec < 0);
+unwind:
+       do_dec_rlimit_put_ucounts(ucounts, iter, type);
+       return 0;
+}
+
 bool is_ucounts_overlimit(struct ucounts *ucounts, enum ucount_type type, unsigned long max)
 {
        struct ucounts *iter;