[Scst-svn] SF.net SVN: scst:[8496] trunk/scst/src/scst_targ.c

[<bva...@us...>]

Revision: 8496
          http://sourceforge.net/p/scst/svn/8496
Author:   bvassche
Date:     2019-08-05 01:43:41 +0000 (Mon, 05 Aug 2019)
Log Message:
-----------
scst: Fix a race condition between LUN translation and LUN removal

Modified Paths:
--------------
    trunk/scst/src/scst_targ.c

Modified: trunk/scst/src/scst_targ.c
===================================================================
--- trunk/scst/src/scst_targ.c	2019-08-05 01:43:03 UTC (rev 8495)
+++ trunk/scst/src/scst_targ.c	2019-08-05 01:43:41 UTC (rev 8496)
@@ -4996,6 +4996,9 @@
 
 		rcu_read_lock();
 		tgt_dev = scst_lookup_tgt_dev(cmd->sess, cmd->lun);
+		if (tgt_dev &&
+		    !atomic_inc_not_zero(&tgt_dev->tgt_dev_cmd_count))
+			tgt_dev = NULL;
 		rcu_read_unlock();
 
 		if (tgt_dev) {
@@ -5014,6 +5017,7 @@
 					"the device will not be visible remotely",
 					(unsigned long long)cmd->lun);
 				nul_dev = true;
+				scst_tgt_dev_dec_cmd_count(tgt_dev);
 			}
 		}
 		if (unlikely(res != 0)) {
@@ -5142,7 +5146,7 @@
 
 		scst_set_cmd_state(cmd, SCST_CMD_STATE_PARSE);
 
-		cnt = atomic_inc_return(&tgt_dev->tgt_dev_cmd_count) - 1;
+		cnt = atomic_read(&tgt_dev->tgt_dev_cmd_count) - 1;
 		if (unlikely(cnt > dev->max_tgt_dev_commands)) {
 			TRACE(TRACE_FLOW_CONTROL,
 				"Too many pending commands (%d) in "

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