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Date:      Thu, 5 Nov 2020 11:19:32 +0000 (UTC)
From:      "Bjoern A. Zeeb" <bz@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org
Subject:   svn commit: r367367 - stable/12/sys/cam
Message-ID:  <202011051119.0A5BJWdo093290@repo.freebsd.org>
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Author: bz
Date: Thu Nov  5 11:19:31 2020
New Revision: 367367
URL: https://svnweb.freebsd.org/changeset/base/367367

Log:
  MFC r365333:
  
    cam_sim: harmonize code related to acquiring a mtx
  
    cam_sim_free(), cam_sim_release(), and cam_sim_hold() all assign
    a mtx variable during declaration and then if NULL or the mtx is
    held may re-asign the variable and/or acquire/release a lock.
  
    Harmonize the code, avoiding double assignments and make it look
    the same for all three function (with cam_sim_free() not needing
    an extra case).
  
    No functional changes intended.

Modified:
  stable/12/sys/cam/cam_sim.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/cam/cam_sim.c
==============================================================================
--- stable/12/sys/cam/cam_sim.c	Thu Nov  5 11:11:50 2020	(r367366)
+++ stable/12/sys/cam/cam_sim.c	Thu Nov  5 11:19:31 2020	(r367367)
@@ -103,14 +103,15 @@ cam_sim_alloc(sim_action_func sim_action, sim_poll_fun
 void
 cam_sim_free(struct cam_sim *sim, int free_devq)
 {
-	struct mtx *mtx = sim->mtx;
+	struct mtx *mtx;
 	int error;
 
-	if (mtx) {
-		mtx_assert(mtx, MA_OWNED);
-	} else {
+	if (sim->mtx == NULL) {
 		mtx = &cam_sim_free_mtx;
 		mtx_lock(mtx);
+	} else {
+		mtx = sim->mtx;
+		mtx_assert(mtx, MA_OWNED);
 	}
 	sim->refcount--;
 	if (sim->refcount > 0) {
@@ -118,7 +119,7 @@ cam_sim_free(struct cam_sim *sim, int free_devq)
 		KASSERT(error == 0, ("invalid error value for msleep(9)"));
 	}
 	KASSERT(sim->refcount == 0, ("sim->refcount == 0"));
-	if (sim->mtx == NULL)
+	if (mtx == &cam_sim_free_mtx)	/* sim->mtx == NULL */
 		mtx_unlock(mtx);
 
 	if (free_devq)
@@ -129,17 +130,16 @@ cam_sim_free(struct cam_sim *sim, int free_devq)
 void
 cam_sim_release(struct cam_sim *sim)
 {
-	struct mtx *mtx = sim->mtx;
+	struct mtx *mtx;
 
-	if (mtx) {
-		if (!mtx_owned(mtx))
-			mtx_lock(mtx);
-		else
-			mtx = NULL;
-	} else {
+	if (sim->mtx == NULL)
 		mtx = &cam_sim_free_mtx;
+	else if (!mtx_owned(sim->mtx))
+		mtx = sim->mtx;
+	else
+		mtx = NULL;	/* We hold the lock. */
+	if (mtx)
 		mtx_lock(mtx);
-	}
 	KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
 	sim->refcount--;
 	if (sim->refcount == 0)
@@ -151,17 +151,16 @@ cam_sim_release(struct cam_sim *sim)
 void
 cam_sim_hold(struct cam_sim *sim)
 {
-	struct mtx *mtx = sim->mtx;
+	struct mtx *mtx;
 
-	if (mtx) {
-		if (!mtx_owned(mtx))
-			mtx_lock(mtx);
-		else
-			mtx = NULL;
-	} else {
+	if (sim->mtx == NULL)
 		mtx = &cam_sim_free_mtx;
+	else if (!mtx_owned(sim->mtx))
+		mtx = sim->mtx;
+	else
+		mtx = NULL;	/* We hold the lock. */
+	if (mtx)
 		mtx_lock(mtx);
-	}
 	KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
 	sim->refcount++;
 	if (mtx)

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