Merge tag 'v4.17-rc4' into patchwork

Linux 4.17-rc4

* tag 'v4.17-rc4': (920 commits)
  Linux 4.17-rc4
  KVM: x86: remove APIC Timer periodic/oneshot spikes
  genksyms: fix typo in parse.tab.{c,h} generation rules
  kbuild: replace hardcoded bison in cmd_bison_h with $(YACC)
  gcc-plugins: fix build condition of SANCOV plugin
  MAINTAINERS: Update Kbuild entry with a few paths
  Revert "usb: host: ehci: Use dma_pool_zalloc()"
  platform/x86: Kconfig: Fix dell-laptop dependency chain.
  platform/x86: asus-wireless: Fix NULL pointer dereference
  arm64: vgic-v2: Fix proxying of cpuif access
  KVM: arm/arm64: vgic_init: Cleanup reference to process_maintenance
  KVM: arm64: Fix order of vcpu_write_sys_reg() arguments
  MAINTAINERS & files: Canonize the e-mails I use at files
  media: imx-media-csi: Fix inconsistent IS_ERR and PTR_ERR
  tools: power/acpi, revert to LD = gcc
  bdi: Fix oops in wb_workfn()
  RDMA/cma: Do not query GID during QP state transition to RTR
  IB/mlx4: Fix integer overflow when calculating optimal MTT size
  IB/hfi1: Fix memory leak in exception path in get_irq_affinity()
  IB/{hfi1, rdmavt}: Fix memory leak in hfi1_alloc_devdata() upon failure
  ...

1 files changed, 9 insertions, 14 deletions

diff --git a/lib/errseq.c b/lib/errseq.c
index df782418b333..81f9e33aa7e7 100644
--- a/lib/errseq.c
+++ b/lib/errseq.c
@@ -111,27 +111,22 @@ EXPORT_SYMBOL(errseq_set);
  * errseq_sample() - Grab current errseq_t value.
  * @eseq: Pointer to errseq_t to be sampled.
  *
- * This function allows callers to sample an errseq_t value, marking it as
- * "seen" if required.
+ * This function allows callers to initialise their errseq_t variable.
+ * If the error has been "seen", new callers will not see an old error.
+ * If there is an unseen error in @eseq, the caller of this function will
+ * see it the next time it checks for an error.
  *
+ * Context: Any context.
  * Return: The current errseq value.
  */
 errseq_t errseq_sample(errseq_t *eseq)
 {
 	errseq_t old = READ_ONCE(*eseq);
-	errseq_t new = old;
 
-	/*
-	 * For the common case of no errors ever having been set, we can skip
-	 * marking the SEEN bit. Once an error has been set, the value will
-	 * never go back to zero.
-	 */
-	if (old != 0) {
-		new |= ERRSEQ_SEEN;
-		if (old != new)
-			cmpxchg(eseq, old, new);
-	}
-	return new;
+	/* If nobody has seen this error yet, then we can be the first. */
+	if (!(old & ERRSEQ_SEEN))
+		old = 0;
+	return old;
 }
 EXPORT_SYMBOL(errseq_sample);