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Date:      Tue, 13 Nov 2018 23:20:56 +0000 (UTC)
From:      Gleb Smirnoff <glebius@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r340415 - in head/sys: kern sys
Message-ID:  <201811132320.wADNKuGo074412@repo.freebsd.org>

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Author: glebius
Date: Tue Nov 13 23:20:55 2018
New Revision: 340415
URL: https://svnweb.freebsd.org/changeset/base/340415

Log:
  The dualism between epoch_tracker and epoch_thread is fragile and
  unnecessary. So, expose CK types to kernel and use a single normal
  structure for epoch_tracker.
  
  Reviewed by:	jtl, gallatin

Modified:
  head/sys/kern/subr_epoch.c
  head/sys/sys/epoch.h

Modified: head/sys/kern/subr_epoch.c
==============================================================================
--- head/sys/kern/subr_epoch.c	Tue Nov 13 23:08:46 2018	(r340414)
+++ head/sys/kern/subr_epoch.c	Tue Nov 13 23:20:55 2018	(r340415)
@@ -55,25 +55,13 @@ __FBSDID("$FreeBSD$");
 
 static MALLOC_DEFINE(M_EPOCH, "epoch", "epoch based reclamation");
 
-typedef struct epoch_thread {
-#ifdef EPOCH_TRACKER_DEBUG
-	uint64_t et_magic_pre;
-#endif
-	TAILQ_ENTRY(epoch_thread) et_link;	/* Epoch queue. */
-	struct thread *et_td;		/* pointer to thread in section */
-	ck_epoch_section_t et_section; /* epoch section object */
-#ifdef EPOCH_TRACKER_DEBUG
-	uint64_t et_magic_post;
-#endif
-} *epoch_thread_t;
-TAILQ_HEAD (epoch_tdlist, epoch_thread);
-
 #ifdef __amd64__
 #define EPOCH_ALIGN CACHE_LINE_SIZE*2
 #else
 #define EPOCH_ALIGN CACHE_LINE_SIZE
 #endif
 
+TAILQ_HEAD (epoch_tdlist, epoch_tracker);
 typedef struct epoch_record {
 	ck_epoch_record_t er_read_record;
 	ck_epoch_record_t er_write_record;
@@ -252,27 +240,25 @@ void
 epoch_enter_preempt(epoch_t epoch, epoch_tracker_t et)
 {
 	struct epoch_record *er;
-	struct epoch_thread *etd;
 	struct thread_lite *td;
 
 	MPASS(cold || epoch != NULL);
 	INIT_CHECK(epoch);
-	etd = (void *)et;
 	MPASS(epoch->e_flags & EPOCH_PREEMPT);
 #ifdef EPOCH_TRACKER_DEBUG
-	etd->et_magic_pre = EPOCH_MAGIC0;
-	etd->et_magic_post = EPOCH_MAGIC1;
+	et->et_magic_pre = EPOCH_MAGIC0;
+	et->et_magic_post = EPOCH_MAGIC1;
 #endif
 	td = (struct thread_lite *)curthread;
-	etd->et_td = (void*)td;
+	et->et_td = (void*)td;
 	td->td_epochnest++;
 	critical_enter();
 	sched_pin_lite(td);
 
 	td->td_pre_epoch_prio = td->td_priority;
 	er = epoch_currecord(epoch);
-	TAILQ_INSERT_TAIL(&er->er_tdlist, etd, et_link);
-	ck_epoch_begin(&er->er_read_record, (ck_epoch_section_t *)&etd->et_section);
+	TAILQ_INSERT_TAIL(&er->er_tdlist, et, et_link);
+	ck_epoch_begin(&er->er_read_record, &et->et_section);
 	critical_exit();
 }
 
@@ -296,7 +282,6 @@ void
 epoch_exit_preempt(epoch_t epoch, epoch_tracker_t et)
 {
 	struct epoch_record *er;
-	struct epoch_thread *etd;
 	struct thread_lite *td;
 
 	INIT_CHECK(epoch);
@@ -307,19 +292,19 @@ epoch_exit_preempt(epoch_t epoch, epoch_tracker_t et)
 	td->td_epochnest--;
 	er = epoch_currecord(epoch);
 	MPASS(epoch->e_flags & EPOCH_PREEMPT);
-	etd = (void *)et;
-	MPASS(etd != NULL);
-	MPASS(etd->et_td == (struct thread *)td);
+	MPASS(et != NULL);
+	MPASS(et->et_td == (struct thread *)td);
 #ifdef EPOCH_TRACKER_DEBUG
-	MPASS(etd->et_magic_pre == EPOCH_MAGIC0);
-	MPASS(etd->et_magic_post == EPOCH_MAGIC1);
-	etd->et_magic_pre = 0;
-	etd->et_magic_post = 0;
+	MPASS(et->et_magic_pre == EPOCH_MAGIC0);
+	MPASS(et->et_magic_post == EPOCH_MAGIC1);
+	et->et_magic_pre = 0;
+	et->et_magic_post = 0;
 #endif
-	etd->et_td = (void*)0xDEADBEEF;
-	ck_epoch_end(&er->er_read_record,
-		(ck_epoch_section_t *)&etd->et_section);
-	TAILQ_REMOVE(&er->er_tdlist, etd, et_link);
+#ifdef INVARIANTS
+	et->et_td = (void*)0xDEADBEEF;
+#endif
+	ck_epoch_end(&er->er_read_record, &et->et_section);
+	TAILQ_REMOVE(&er->er_tdlist, et, et_link);
 	er->er_gen++;
 	if (__predict_false(td->td_pre_epoch_prio != td->td_priority))
 		epoch_adjust_prio((struct thread *)td, td->td_pre_epoch_prio);
@@ -351,7 +336,7 @@ epoch_block_handler_preempt(struct ck_epoch *global __
 {
 	epoch_record_t record;
 	struct thread *td, *owner, *curwaittd;
-	struct epoch_thread *tdwait;
+	struct epoch_tracker *tdwait;
 	struct turnstile *ts;
 	struct lock_object *lock;
 	int spincount, gen;
@@ -633,7 +618,7 @@ epoch_call_task(void *arg __unused)
 int
 in_epoch_verbose(epoch_t epoch, int dump_onfail)
 {
-	struct epoch_thread *tdwait;
+	struct epoch_tracker *tdwait;
 	struct thread *td;
 	epoch_record_t er;
 

Modified: head/sys/sys/epoch.h
==============================================================================
--- head/sys/sys/epoch.h	Tue Nov 13 23:08:46 2018	(r340414)
+++ head/sys/sys/epoch.h	Tue Nov 13 23:20:55 2018	(r340415)
@@ -30,31 +30,16 @@
 #ifndef _SYS_EPOCH_H_
 #define _SYS_EPOCH_H_
 
-/*
- * XXXGL: temporarily keep epoch_tracker exposed to userland until
- * we remove trackers embedded into network structs.
- */
-
 struct epoch_context {
 	void   *data[2];
 } __aligned(sizeof(void *));
 
 typedef struct epoch_context *epoch_context_t;
 
-struct epoch_tracker {
-	void *datap[3];
-#ifdef EPOCH_TRACKER_DEBUG
-	int datai[5];
-#else
-	int datai[1];
-#endif
-}  __aligned(sizeof(void *));
-
-typedef struct epoch_tracker *epoch_tracker_t;
-
 #ifdef _KERNEL
 #include <sys/lock.h>
 #include <sys/pcpu.h>
+#include <ck_epoch.h>
 
 struct epoch;
 typedef struct epoch *epoch_t;
@@ -64,6 +49,21 @@ typedef struct epoch *epoch_t;
 
 extern epoch_t global_epoch;
 extern epoch_t global_epoch_preempt;
+
+struct epoch_tracker {
+#ifdef	EPOCH_TRACKER_DEBUG
+#define	EPOCH_MAGIC0 0xFADECAFEF00DD00D
+#define	EPOCH_MAGIC1 0xBADDBABEDEEDFEED
+	uint64_t et_magic_pre;
+#endif
+	TAILQ_ENTRY(epoch_tracker) et_link;
+	struct thread *et_td;
+	ck_epoch_section_t et_section;
+#ifdef	EPOCH_TRACKER_DEBUG
+	uint64_t et_magic_post;
+#endif
+}  __aligned(sizeof(void *));
+typedef struct epoch_tracker *epoch_tracker_t;
 
 epoch_t	epoch_alloc(int flags);
 void	epoch_free(epoch_t epoch);



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