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Date:      Fri, 25 May 2012 07:57:17 +0000 (UTC)
From:      Alexander Motin <mav@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r235980 - head/sys/cam/scsi
Message-ID:  <201205250757.q4P7vIC0089168@svn.freebsd.org>
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Author: mav
Date: Fri May 25 07:57:17 2012
New Revision: 235980
URL: http://svn.freebsd.org/changeset/base/235980

Log:
  Remove sleep() from invalidate call in ses driver, waiting for daemon
  process exit. Instead use CAM's standard reference counting to prevent
  periph going away until process won't complete. I think that sleep in
  single CAM SWI thread is not a good idea and may lead to deadlocks if
  daemon process waits for some command completion. Combined with recent
  patch avoiding use of CAM SWI for ATA it just causes panics because of
  sleeps prohibited in interrupt thread context.

Modified:
  head/sys/cam/scsi/scsi_enc.c

Modified: head/sys/cam/scsi/scsi_enc.c
==============================================================================
--- head/sys/cam/scsi/scsi_enc.c	Fri May 25 07:46:24 2012	(r235979)
+++ head/sys/cam/scsi/scsi_enc.c	Fri May 25 07:57:17 2012	(r235980)
@@ -136,15 +136,8 @@ enc_oninvalidate(struct cam_periph *peri
 	 */
 	enc->enc_flags |= ENC_FLAG_SHUTDOWN;
 	if (enc->enc_daemon != NULL) {
-		/* Signal and wait for the ses daemon to terminate. */
+		/* Signal the ses daemon to terminate. */
 		wakeup(enc->enc_daemon);
-		/*
-		 * We're called with the SIM mutex held, but we're dropping
-		 * the update mutex here on sleep.  So we have to manually
-		 * drop the SIM mutex.
-		 */
-		cam_periph_sleep(enc->periph, enc->enc_daemon,
-				 PUSER, "thtrm", 0);
 	}
 	callout_drain(&enc->status_updater);
 
@@ -839,6 +832,7 @@ enc_daemon(void *arg)
 	}
 	enc->enc_daemon = NULL;
 	cam_periph_unlock(enc->periph);
+	cam_periph_release(enc->periph);
 	kproc_exit(0);
 }
 
@@ -849,6 +843,9 @@ enc_kproc_init(enc_softc_t *enc)
 
 	callout_init_mtx(&enc->status_updater, enc->periph->sim->mtx, 0);
 
+	if (cam_periph_acquire(enc->periph) != CAM_REQ_CMP)
+		return (ENXIO);
+
 	result = kproc_create(enc_daemon, enc, &enc->enc_daemon, /*flags*/0,
 			      /*stackpgs*/0, "enc_daemon%d",
 			      enc->periph->unit_number);
@@ -857,7 +854,8 @@ enc_kproc_init(enc_softc_t *enc)
 		cam_periph_lock(enc->periph);
 		enc->enc_vec.poll_status(enc);
 		cam_periph_unlock(enc->periph);
-	}
+	} else
+		cam_periph_release(enc->periph);
 	return (result);
 }
  
@@ -955,7 +953,7 @@ enc_ctor(struct cam_periph *periph, void
 		err = enc_kproc_init(enc);
 		if (err) {
 			xpt_print(periph->path,
-				  "error %d string enc_daemon\n", err);
+				  "error %d starting enc_daemon\n", err);
 			goto out;
 		}
 	}

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