Merge branches 'clockevents/4.4-fixes' and 'clockevents/4.5-fixes' of http://git.linaro.org/people/daniel.lezcano/linux into timers/urgent

Pull in fixes from Daniel Lezcano:

 - Fix the vt8500 timer leading to a system lock up when dealing with too
   small delta (Roman Volkov)

 - Select the CLKSRC_MMIO when the fsl_ftm_timer is enabled with COMPILE_TEST
   (Daniel Lezcano)

 - Prevent to compile timers using the 'iomem' API when the architecture has
   not HAS_IOMEM set (Richard Weinberger)

1 files changed, 26 insertions, 12 deletions

diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c
index 845769e41332..c8c8b9ed02e0 100644
--- a/arch/arm/mm/context.c
+++ b/arch/arm/mm/context.c
@@ -165,13 +165,28 @@ static void flush_context(unsigned int cpu)
                 __flush_icache_all();
 }
 
-static int is_reserved_asid(u64 asid)
+static bool check_update_reserved_asid(u64 asid, u64 newasid)
 {
         int cpu;
-        for_each_possible_cpu(cpu)
-                if (per_cpu(reserved_asids, cpu) == asid)
-                        return 1;
-        return 0;
+        bool hit = false;
+
+        /*
+         * Iterate over the set of reserved ASIDs looking for a match.
+         * If we find one, then we can update our mm to use newasid
+         * (i.e. the same ASID in the current generation) but we can't
+         * exit the loop early, since we need to ensure that all copies
+         * of the old ASID are updated to reflect the mm. Failure to do
+         * so could result in us missing the reserved ASID in a future
+         * generation.
+         */
+        for_each_possible_cpu(cpu) {
+                if (per_cpu(reserved_asids, cpu) == asid) {
+                        hit = true;
+                        per_cpu(reserved_asids, cpu) = newasid;
+                }
+        }
+
+        return hit;
 }
 
 static u64 new_context(struct mm_struct *mm, unsigned int cpu)
@@ -181,12 +196,14 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu)
         u64 generation = atomic64_read(&asid_generation);
 
         if (asid != 0) {
+                u64 newasid = generation | (asid & ~ASID_MASK);
+
                 /*
                  * If our current ASID was active during a rollover, we
                  * can continue to use it and this was just a false alarm.
                  */
-                if (is_reserved_asid(asid))
-                        return generation | (asid & ~ASID_MASK);
+                if (check_update_reserved_asid(asid, newasid))
+                        return newasid;
 
                 /*
                  * We had a valid ASID in a previous life, so try to re-use
@@ -194,7 +211,7 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu)
                  */
                 asid &= ~ASID_MASK;
                 if (!__test_and_set_bit(asid, asid_map))
-                        goto bump_gen;
+                        return newasid;
         }
 
         /*
@@ -216,11 +233,8 @@ static u64 new_context(struct mm_struct *mm, unsigned int cpu)
 
         __set_bit(asid, asid_map);
         cur_idx = asid;
-
-bump_gen:
-        asid |= generation;
         cpumask_clear(mm_cpumask(mm));
-        return asid;
+        return asid | generation;
 }
 
 void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk)