Merge tag 'fixes-for-v4.11-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb into usb-linus

Felipe writes:

usb: fixes for v4.11-rc4

f_acm got an endianness fix by Oliver Neukum. This has been around for a
long time but it's finally fixed.

f_hid learned that it should never access hidg->req without first
grabbing the spinlock.

Roger Quadros fixed two bugs in the f_uvc function driver.

Janusz Dziedzic fixed a very peculiar bug with EP0, one that's rather
difficult to trigger. When we're dealing with bounced EP0 requests, we
should delay unmap until after ->complete() is called.

UDC class got a use-after-free fix.

1 files changed, 14 insertions, 2 deletions

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 349d4d17aa7f..2aa1ad194db2 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2101,8 +2101,8 @@ static int x86_pmu_event_init(struct perf_event *event)
 
 static void refresh_pce(void *ignored)
 {
-	if (current->mm)
-		load_mm_cr4(current->mm);
+	if (current->active_mm)
+		load_mm_cr4(current->active_mm);
 }
 
 static void x86_pmu_event_mapped(struct perf_event *event)
@@ -2110,6 +2110,18 @@ static void x86_pmu_event_mapped(struct perf_event *event)
 	if (!(event->hw.flags & PERF_X86_EVENT_RDPMC_ALLOWED))
 		return;
 
+	/*
+	 * This function relies on not being called concurrently in two
+	 * tasks in the same mm.  Otherwise one task could observe
+	 * perf_rdpmc_allowed > 1 and return all the way back to
+	 * userspace with CR4.PCE clear while another task is still
+	 * doing on_each_cpu_mask() to propagate CR4.PCE.
+	 *
+	 * For now, this can't happen because all callers hold mmap_sem
+	 * for write.  If this changes, we'll need a different solution.
+	 */
+	lockdep_assert_held_exclusive(&current->mm->mmap_sem);
+
 	if (atomic_inc_return(&current->mm->context.perf_rdpmc_allowed) == 1)
 		on_each_cpu_mask(mm_cpumask(current->mm), refresh_pce, NULL, 1);
 }