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Date:      Fri, 14 Feb 2020 23:15:41 +0000 (UTC)
From:      Mateusz Guzik <mjg@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r357940 - in head/sys: amd64/amd64 sys x86/x86
Message-ID:  <202002142315.01ENFfZ3067165@repo.freebsd.org>
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Author: mjg
Date: Fri Feb 14 23:15:41 2020
New Revision: 357940
URL: https://svnweb.freebsd.org/changeset/base/357940

Log:
  Make atomic_load_ptr type-aware
  
  Returned value has type based on the argument, meaning consumers no longer
  have to cast in the commmon case.
  
  This commit keeps the kernel compilable without patching the rest.

Modified:
  head/sys/amd64/amd64/pmap.c
  head/sys/sys/_cscan_atomic.h
  head/sys/sys/atomic_common.h
  head/sys/x86/x86/mp_x86.c

Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c	Fri Feb 14 22:32:33 2020	(r357939)
+++ head/sys/amd64/amd64/pmap.c	Fri Feb 14 23:15:41 2020	(r357940)
@@ -796,7 +796,7 @@ again:
 	PV_STAT(i = 0);
 	for (p = &pmap_invl_gen_head;; p = prev.next) {
 		PV_STAT(i++);
-		prevl = atomic_load_ptr(&p->next);
+		prevl = (uintptr_t)atomic_load_ptr(&p->next);
 		if ((prevl & PMAP_INVL_GEN_NEXT_INVALID) != 0) {
 			PV_STAT(atomic_add_long(&invl_start_restart, 1));
 			lock_delay(&lda);
@@ -903,7 +903,7 @@ pmap_delayed_invl_finish_u(void)
 
 again:
 	for (p = &pmap_invl_gen_head; p != NULL; p = (void *)prevl) {
-		prevl = atomic_load_ptr(&p->next);
+		prevl = (uintptr_t)atomic_load_ptr(&p->next);
 		if ((prevl & PMAP_INVL_GEN_NEXT_INVALID) != 0) {
 			PV_STAT(atomic_add_long(&invl_finish_restart, 1));
 			lock_delay(&lda);
@@ -954,7 +954,7 @@ DB_SHOW_COMMAND(di_queue, pmap_di_queue)
 
 	for (p = &pmap_invl_gen_head, first = true; p != NULL; p = pn,
 	    first = false) {
-		nextl = atomic_load_ptr(&p->next);
+		nextl = (uintptr_t)atomic_load_ptr(&p->next);
 		pn = (void *)(nextl & ~PMAP_INVL_GEN_NEXT_INVALID);
 		td = first ? NULL : __containerof(p, struct thread,
 		    td_md.md_invl_gen);

Modified: head/sys/sys/_cscan_atomic.h
==============================================================================
--- head/sys/sys/_cscan_atomic.h	Fri Feb 14 22:32:33 2020	(r357939)
+++ head/sys/sys/_cscan_atomic.h	Fri Feb 14 23:15:41 2020	(r357940)
@@ -170,7 +170,11 @@ void	kcsan_atomic_thread_fence_seq_cst(void);
 #define	atomic_fcmpset_acq_ptr		kcsan_atomic_fcmpset_acq_ptr
 #define	atomic_fcmpset_rel_ptr		kcsan_atomic_fcmpset_rel_ptr
 #define	atomic_fetchadd_ptr		kcsan_atomic_fetchadd_ptr
-#define	atomic_load_ptr(x)		kcsan_atomic_load_ptr((volatile uintptr_t *)(x))
+#define	atomic_load_ptr(x)		({					\
+	__typeof(*x) __retptr;							\
+	__retptr = (void *)kcsan_atomic_load_ptr((volatile uintptr_t *)(x));	\
+	__retptr;								\
+})
 #define	atomic_load_acq_ptr		kcsan_atomic_load_acq_ptr
 #define	atomic_readandclear_ptr		kcsan_atomic_readandclear_ptr
 #define	atomic_set_ptr			kcsan_atomic_set_ptr

Modified: head/sys/sys/atomic_common.h
==============================================================================
--- head/sys/sys/atomic_common.h	Fri Feb 14 22:32:33 2020	(r357939)
+++ head/sys/sys/atomic_common.h	Fri Feb 14 23:15:41 2020	(r357940)
@@ -41,7 +41,7 @@
 #define	atomic_load_short(p)	(*(volatile u_short *)(p))
 #define	atomic_load_int(p)	(*(volatile u_int *)(p))
 #define	atomic_load_long(p)	(*(volatile u_long *)(p))
-#define	atomic_load_ptr(p)	(*(volatile uintptr_t*)(p))
+#define	atomic_load_ptr(p)	(*(volatile __typeof(p))(p))
 #define	atomic_load_8(p)	(*(volatile uint8_t *)(p))
 #define	atomic_load_16(p)	(*(volatile uint16_t *)(p))
 #define	atomic_load_32(p)	(*(volatile uint32_t *)(p))

Modified: head/sys/x86/x86/mp_x86.c
==============================================================================
--- head/sys/x86/x86/mp_x86.c	Fri Feb 14 22:32:33 2020	(r357939)
+++ head/sys/x86/x86/mp_x86.c	Fri Feb 14 23:15:41 2020	(r357940)
@@ -1106,7 +1106,7 @@ smp_after_idle_runnable(void *arg __unused)
 
 	for (cpu = 1; cpu < mp_ncpus; cpu++) {
 		pc = pcpu_find(cpu);
-		while (atomic_load_ptr(&pc->pc_curpcb) == (uintptr_t)NULL)
+		while (atomic_load_ptr(&pc->pc_curpcb) == NULL)
 			cpu_spinwait();
 		kmem_free((vm_offset_t)bootstacks[cpu], kstack_pages *
 		    PAGE_SIZE);

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