[Scst-svn] SF.net SVN: scst:[5851] trunk

[<vl...@us...>]

Revision: 5851
          http://sourceforge.net/p/scst/svn/5851
Author:   vlnb
Date:     2014-10-17 02:35:01 +0000 (Fri, 17 Oct 2014)
Log Message:
-----------
scst, iscsi-scst: Add thread_pid attribute

For SCST devices with a short name determining which SCST command
threads serve a given LUN requires an (expensive) walk of the
process table. For SCST devices with a long name it is not possible
to determine unambiguously which command threads serve a given
LUN. Hence add a thread_pid sysfs attribute that makes it easy to
figure out which command threads serve a LUN.

Signed-off-by: Bart Van Assche <bva...@ac...>

Modified Paths:
--------------
    trunk/iscsi-scst/README
    trunk/iscsi-scst/kernel/session.c
    trunk/scst/README
    trunk/scst/README_in-tree
    trunk/scst/src/scst_sysfs.c

Modified: trunk/iscsi-scst/README
===================================================================
--- trunk/iscsi-scst/README	2014-10-17 02:32:28 UTC (rev 5850)
+++ trunk/iscsi-scst/README	2014-10-17 02:35:01 UTC (rev 5851)
@@ -332,9 +332,14 @@
 
  - tid - TID of this target.
 
-Subdirectory "sessions" contains one subdirectory for each connected
-session with name equal to name of the connected initiator.
+The "sessions" subdirectory contains the following attribute:
 
+ - thread_pid - the process identifiers (PIDs) of the iscsird and iscsiwr
+   threads that process SCSI commands associated with this session.
+
+Additionally, the "sessions" subdirectory contains one subdirectory for each
+connected session with name equal to name of the connected initiator.
+
 Each session subdirectory contains the following entries:
 
  - One subdirectory for each TCP connection in this session. ISCSI-SCST

Modified: trunk/iscsi-scst/kernel/session.c
===================================================================
--- trunk/iscsi-scst/kernel/session.c	2014-10-17 02:32:28 UTC (rev 5850)
+++ trunk/iscsi-scst/kernel/session.c	2014-10-17 02:35:01 UTC (rev 5851)
@@ -560,6 +560,37 @@
 static struct kobj_attribute iscsi_sess_attr_reinstating =
 	__ATTR(reinstating, S_IRUGO, iscsi_sess_reinstating_show, NULL);
 
+static ssize_t iscsi_sess_thread_pid_show(struct kobject *kobj,
+	struct kobj_attribute *attr, char *buf)
+{
+	struct scst_session *scst_sess = container_of(kobj, struct scst_session,
+						      sess_kobj);
+	struct iscsi_session *sess = scst_sess_get_tgt_priv(scst_sess);
+	struct iscsi_thread_pool *thr_pool = sess->sess_thr_pool;
+	struct iscsi_thread *t;
+	int res = -ENOENT;
+
+	if (!thr_pool)
+		goto out;
+
+	res = 0;
+
+	mutex_lock(&thr_pool->tp_mutex);
+	list_for_each_entry(t, &thr_pool->threads_list, threads_list_entry)
+		res += scnprintf(buf + res, PAGE_SIZE - res, "%d%s",
+				 task_pid_vnr(t->thr),
+				 list_is_last(&t->threads_list_entry,
+					      &thr_pool->threads_list) ?
+				 "\n" : " ");
+	mutex_unlock(&thr_pool->tp_mutex);
+
+out:
+	return res;
+}
+
+static struct kobj_attribute iscsi_sess_thread_pid =
+	__ATTR(thread_pid, S_IRUGO, iscsi_sess_thread_pid_show, NULL);
+
 const struct attribute *iscsi_sess_attrs[] = {
 	&iscsi_sess_attr_initial_r2t.attr,
 	&iscsi_sess_attr_immediate_data.attr,
@@ -572,6 +603,7 @@
 	&iscsi_sess_attr_data_digest.attr,
 	&iscsi_attr_sess_sid.attr,
 	&iscsi_sess_attr_reinstating.attr,
+	&iscsi_sess_thread_pid.attr,
 	NULL,
 };
 

Modified: trunk/scst/README
===================================================================
--- trunk/scst/README	2014-10-17 02:32:28 UTC (rev 5850)
+++ trunk/scst/README	2014-10-17 02:35:01 UTC (rev 5851)
@@ -695,7 +695,11 @@
  - active_commands - contains number of active, i.e. not yet or being
    executed, SCSI commands for lun<X> in session <sess>.
 
+ - thread_pid - contains a single line with all the process identifiers
+   (PIDs) of the kernel threads that process SCSI commands intended for
+   lun<X> in session <sess>.
 
+
 Access and devices visibility management (LUN masking)
 ------------------------------------------------------
 

Modified: trunk/scst/README_in-tree
===================================================================
--- trunk/scst/README_in-tree	2014-10-17 02:32:28 UTC (rev 5850)
+++ trunk/scst/README_in-tree	2014-10-17 02:35:01 UTC (rev 5851)
@@ -557,7 +557,11 @@
  - active_commands - contains number of active, i.e. not yet or being
    executed, SCSI commands for lun<X> in session <sess>.
 
+ - thread_pid - contains a single line with all the process identifiers
+   (PIDs) of the kernel threads that process SCSI commands intended for
+   lun<X> in session <sess>.
 
+
 Access and devices visibility management (LUN masking)
 ------------------------------------------------------
 

Modified: trunk/scst/src/scst_sysfs.c
===================================================================
--- trunk/scst/src/scst_sysfs.c	2014-10-17 02:32:28 UTC (rev 5850)
+++ trunk/scst/src/scst_sysfs.c	2014-10-17 02:35:01 UTC (rev 5851)
@@ -3506,6 +3506,31 @@
 
 #endif /* CONFIG_SCST_MEASURE_LATENCY */
 
+static ssize_t scst_tgt_dev_thread_pid_show(struct kobject *kobj,
+					    struct kobj_attribute *attr,
+					    char *buffer)
+{
+	struct scst_tgt_dev *tgt_dev =
+		container_of(kobj, struct scst_tgt_dev, tgt_dev_kobj);
+	struct scst_cmd_threads *cmd_threads = tgt_dev->active_cmd_threads;
+	struct scst_cmd_thread_t *t;
+	int res = 0;
+
+	spin_lock(&cmd_threads->thr_lock);
+	list_for_each_entry(t, &cmd_threads->threads_list, thread_list_entry)
+		res += scnprintf(buffer + res, PAGE_SIZE - res, "%d%s",
+				 task_pid_vnr(t->cmd_thread),
+				 list_is_last(&t->thread_list_entry,
+					      &cmd_threads->threads_list) ?
+				 "\n" : " ");
+	spin_unlock(&cmd_threads->thr_lock);
+
+	return res;
+}
+
+static struct kobj_attribute tgt_dev_thread_pid_attr =
+	__ATTR(thread_pid, S_IRUGO, scst_tgt_dev_thread_pid_show, NULL);
+
 static ssize_t scst_tgt_dev_active_commands_show(struct kobject *kobj,
 			    struct kobj_attribute *attr, char *buf)
 {
@@ -3524,6 +3549,7 @@
 		scst_tgt_dev_active_commands_show, NULL);
 
 static struct attribute *scst_tgt_dev_attrs[] = {
+	&tgt_dev_thread_pid_attr.attr,
 	&tgt_dev_active_commands_attr.attr,
 #ifdef CONFIG_SCST_MEASURE_LATENCY
 	&tgt_dev_latency_attr.attr,

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