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linux/drivers/target/iscsi/iscsi_target_tq.c
Roland Dreier 1f981de55a iscsi-target: Use list_first_entry() where appropriate 
Instead of using the obfuscated pattern of

	list_for_each_entry(var, list, ...)
		break;

to set var to the first entry of a list, use the straightforward

	var = list_first_entry(list, ...);

Reported-by: Joern Engel <joern@logfs.org>
Signed-off-by: Roland Dreier <roland@purestorage.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
2012-11-06 20:55:45 -08:00

545 lines
14 KiB
C
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/*******************************************************************************
* This file contains the iSCSI Login Thread and Thread Queue functions.
*
* \u00a9 Copyright 2007-2011 RisingTide Systems LLC.
*
* Licensed to the Linux Foundation under the General Public License (GPL) version 2.
*
* Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
******************************************************************************/
#include <linux/kthread.h>
#include <linux/list.h>
#include <linux/bitmap.h>
#include "iscsi_target_core.h"
#include "iscsi_target_tq.h"
#include "iscsi_target.h"
static LIST_HEAD(active_ts_list);
static LIST_HEAD(inactive_ts_list);
static DEFINE_SPINLOCK(active_ts_lock);
static DEFINE_SPINLOCK(inactive_ts_lock);
static DEFINE_SPINLOCK(ts_bitmap_lock);
static void iscsi_add_ts_to_active_list(struct iscsi_thread_set *ts)
{
spin_lock(&active_ts_lock);
list_add_tail(&ts->ts_list, &active_ts_list);
iscsit_global->active_ts++;
spin_unlock(&active_ts_lock);
}
static void iscsi_add_ts_to_inactive_list(struct iscsi_thread_set *ts)
{
spin_lock(&inactive_ts_lock);
list_add_tail(&ts->ts_list, &inactive_ts_list);
iscsit_global->inactive_ts++;
spin_unlock(&inactive_ts_lock);
}
static void iscsi_del_ts_from_active_list(struct iscsi_thread_set *ts)
{
spin_lock(&active_ts_lock);
list_del(&ts->ts_list);
iscsit_global->active_ts--;
spin_unlock(&active_ts_lock);
}
static struct iscsi_thread_set *iscsi_get_ts_from_inactive_list(void)
{
struct iscsi_thread_set *ts;
spin_lock(&inactive_ts_lock);
if (list_empty(&inactive_ts_list)) {
spin_unlock(&inactive_ts_lock);
return NULL;
}
ts = list_first_entry(&inactive_ts_list, struct iscsi_thread_set, ts_list);
list_del(&ts->ts_list);
iscsit_global->inactive_ts--;
spin_unlock(&inactive_ts_lock);
return ts;
}
int iscsi_allocate_thread_sets(u32 thread_pair_count)
{
int allocated_thread_pair_count = 0, i, thread_id;
struct iscsi_thread_set *ts = NULL;
for (i = 0; i < thread_pair_count; i++) {
ts = kzalloc(sizeof(struct iscsi_thread_set), GFP_KERNEL);
if (!ts) {
pr_err("Unable to allocate memory for"
" thread set.\n");
return allocated_thread_pair_count;
}
/*
* Locate the next available regision in the thread_set_bitmap
*/
spin_lock(&ts_bitmap_lock);
thread_id = bitmap_find_free_region(iscsit_global->ts_bitmap,
iscsit_global->ts_bitmap_count, get_order(1));
spin_unlock(&ts_bitmap_lock);
if (thread_id < 0) {
pr_err("bitmap_find_free_region() failed for"
" thread_set_bitmap\n");
kfree(ts);
return allocated_thread_pair_count;
}
ts->thread_id = thread_id;
ts->status = ISCSI_THREAD_SET_FREE;
INIT_LIST_HEAD(&ts->ts_list);
spin_lock_init(&ts->ts_state_lock);
init_completion(&ts->rx_post_start_comp);
init_completion(&ts->tx_post_start_comp);
init_completion(&ts->rx_restart_comp);
init_completion(&ts->tx_restart_comp);
init_completion(&ts->rx_start_comp);
init_completion(&ts->tx_start_comp);
ts->create_threads = 1;
ts->tx_thread = kthread_run(iscsi_target_tx_thread, ts, "%s",
ISCSI_TX_THREAD_NAME);
if (IS_ERR(ts->tx_thread)) {
dump_stack();
pr_err("Unable to start iscsi_target_tx_thread\n");
break;
}
ts->rx_thread = kthread_run(iscsi_target_rx_thread, ts, "%s",
ISCSI_RX_THREAD_NAME);
if (IS_ERR(ts->rx_thread)) {
kthread_stop(ts->tx_thread);
pr_err("Unable to start iscsi_target_rx_thread\n");
break;
}
ts->create_threads = 0;
iscsi_add_ts_to_inactive_list(ts);
allocated_thread_pair_count++;
}
pr_debug("Spawned %d thread set(s) (%d total threads).\n",
allocated_thread_pair_count, allocated_thread_pair_count * 2);
return allocated_thread_pair_count;
}
void iscsi_deallocate_thread_sets(void)
{
u32 released_count = 0;
struct iscsi_thread_set *ts = NULL;
while ((ts = iscsi_get_ts_from_inactive_list())) {
spin_lock_bh(&ts->ts_state_lock);
ts->status = ISCSI_THREAD_SET_DIE;
spin_unlock_bh(&ts->ts_state_lock);
if (ts->rx_thread) {
send_sig(SIGINT, ts->rx_thread, 1);
kthread_stop(ts->rx_thread);
}
if (ts->tx_thread) {
send_sig(SIGINT, ts->tx_thread, 1);
kthread_stop(ts->tx_thread);
}
/*
* Release this thread_id in the thread_set_bitmap
*/
spin_lock(&ts_bitmap_lock);
bitmap_release_region(iscsit_global->ts_bitmap,
ts->thread_id, get_order(1));
spin_unlock(&ts_bitmap_lock);
released_count++;
kfree(ts);
}
if (released_count)
pr_debug("Stopped %d thread set(s) (%d total threads)."
"\n", released_count, released_count * 2);
}
static void iscsi_deallocate_extra_thread_sets(void)
{
u32 orig_count, released_count = 0;
struct iscsi_thread_set *ts = NULL;
orig_count = TARGET_THREAD_SET_COUNT;
while ((iscsit_global->inactive_ts + 1) > orig_count) {
ts = iscsi_get_ts_from_inactive_list();
if (!ts)
break;
spin_lock_bh(&ts->ts_state_lock);
ts->status = ISCSI_THREAD_SET_DIE;
spin_unlock_bh(&ts->ts_state_lock);
if (ts->rx_thread) {
send_sig(SIGINT, ts->rx_thread, 1);
kthread_stop(ts->rx_thread);
}
if (ts->tx_thread) {
send_sig(SIGINT, ts->tx_thread, 1);
kthread_stop(ts->tx_thread);
}
/*
* Release this thread_id in the thread_set_bitmap
*/
spin_lock(&ts_bitmap_lock);
bitmap_release_region(iscsit_global->ts_bitmap,
ts->thread_id, get_order(1));
spin_unlock(&ts_bitmap_lock);
released_count++;
kfree(ts);
}
if (released_count) {
pr_debug("Stopped %d thread set(s) (%d total threads)."
"\n", released_count, released_count * 2);
}
}
void iscsi_activate_thread_set(struct iscsi_conn *conn, struct iscsi_thread_set *ts)
{
iscsi_add_ts_to_active_list(ts);
spin_lock_bh(&ts->ts_state_lock);
conn->thread_set = ts;
ts->conn = conn;
spin_unlock_bh(&ts->ts_state_lock);
/*
* Start up the RX thread and wait on rx_post_start_comp. The RX
* Thread will then do the same for the TX Thread in
* iscsi_rx_thread_pre_handler().
*/
complete(&ts->rx_start_comp);
wait_for_completion(&ts->rx_post_start_comp);
}
struct iscsi_thread_set *iscsi_get_thread_set(void)
{
int allocate_ts = 0;
struct completion comp;
struct iscsi_thread_set *ts = NULL;
/*
* If no inactive thread set is available on the first call to
* iscsi_get_ts_from_inactive_list(), sleep for a second and
* try again. If still none are available after two attempts,
* allocate a set ourselves.
*/
get_set:
ts = iscsi_get_ts_from_inactive_list();
if (!ts) {
if (allocate_ts == 2)
iscsi_allocate_thread_sets(1);
init_completion(&comp);
wait_for_completion_timeout(&comp, 1 * HZ);
allocate_ts++;
goto get_set;
}
ts->delay_inactive = 1;
ts->signal_sent = 0;
ts->thread_count = 2;
init_completion(&ts->rx_restart_comp);
init_completion(&ts->tx_restart_comp);
return ts;
}
void iscsi_set_thread_clear(struct iscsi_conn *conn, u8 thread_clear)
{
struct iscsi_thread_set *ts = NULL;
if (!conn->thread_set) {
pr_err("struct iscsi_conn->thread_set is NULL\n");
return;
}
ts = conn->thread_set;
spin_lock_bh(&ts->ts_state_lock);
ts->thread_clear &= ~thread_clear;
if ((thread_clear & ISCSI_CLEAR_RX_THREAD) &&
(ts->blocked_threads & ISCSI_BLOCK_RX_THREAD))
complete(&ts->rx_restart_comp);
else if ((thread_clear & ISCSI_CLEAR_TX_THREAD) &&
(ts->blocked_threads & ISCSI_BLOCK_TX_THREAD))
complete(&ts->tx_restart_comp);
spin_unlock_bh(&ts->ts_state_lock);
}
void iscsi_set_thread_set_signal(struct iscsi_conn *conn, u8 signal_sent)
{
struct iscsi_thread_set *ts = NULL;
if (!conn->thread_set) {
pr_err("struct iscsi_conn->thread_set is NULL\n");
return;
}
ts = conn->thread_set;
spin_lock_bh(&ts->ts_state_lock);
ts->signal_sent |= signal_sent;
spin_unlock_bh(&ts->ts_state_lock);
}
int iscsi_release_thread_set(struct iscsi_conn *conn)
{
int thread_called = 0;
struct iscsi_thread_set *ts = NULL;
if (!conn || !conn->thread_set) {
pr_err("connection or thread set pointer is NULL\n");
BUG();
}
ts = conn->thread_set;
spin_lock_bh(&ts->ts_state_lock);
ts->status = ISCSI_THREAD_SET_RESET;
if (!strncmp(current->comm, ISCSI_RX_THREAD_NAME,
strlen(ISCSI_RX_THREAD_NAME)))
thread_called = ISCSI_RX_THREAD;
else if (!strncmp(current->comm, ISCSI_TX_THREAD_NAME,
strlen(ISCSI_TX_THREAD_NAME)))
thread_called = ISCSI_TX_THREAD;
if (ts->rx_thread && (thread_called == ISCSI_TX_THREAD) &&
(ts->thread_clear & ISCSI_CLEAR_RX_THREAD)) {
if (!(ts->signal_sent & ISCSI_SIGNAL_RX_THREAD)) {
send_sig(SIGINT, ts->rx_thread, 1);
ts->signal_sent |= ISCSI_SIGNAL_RX_THREAD;
}
ts->blocked_threads |= ISCSI_BLOCK_RX_THREAD;
spin_unlock_bh(&ts->ts_state_lock);
wait_for_completion(&ts->rx_restart_comp);
spin_lock_bh(&ts->ts_state_lock);
ts->blocked_threads &= ~ISCSI_BLOCK_RX_THREAD;
}
if (ts->tx_thread && (thread_called == ISCSI_RX_THREAD) &&
(ts->thread_clear & ISCSI_CLEAR_TX_THREAD)) {
if (!(ts->signal_sent & ISCSI_SIGNAL_TX_THREAD)) {
send_sig(SIGINT, ts->tx_thread, 1);
ts->signal_sent |= ISCSI_SIGNAL_TX_THREAD;
}
ts->blocked_threads |= ISCSI_BLOCK_TX_THREAD;
spin_unlock_bh(&ts->ts_state_lock);
wait_for_completion(&ts->tx_restart_comp);
spin_lock_bh(&ts->ts_state_lock);
ts->blocked_threads &= ~ISCSI_BLOCK_TX_THREAD;
}
ts->conn = NULL;
ts->status = ISCSI_THREAD_SET_FREE;
spin_unlock_bh(&ts->ts_state_lock);
return 0;
}
int iscsi_thread_set_force_reinstatement(struct iscsi_conn *conn)
{
struct iscsi_thread_set *ts;
if (!conn->thread_set)
return -1;
ts = conn->thread_set;
spin_lock_bh(&ts->ts_state_lock);
if (ts->status != ISCSI_THREAD_SET_ACTIVE) {
spin_unlock_bh(&ts->ts_state_lock);
return -1;
}
if (ts->tx_thread && (!(ts->signal_sent & ISCSI_SIGNAL_TX_THREAD))) {
send_sig(SIGINT, ts->tx_thread, 1);
ts->signal_sent |= ISCSI_SIGNAL_TX_THREAD;
}
if (ts->rx_thread && (!(ts->signal_sent & ISCSI_SIGNAL_RX_THREAD))) {
send_sig(SIGINT, ts->rx_thread, 1);
ts->signal_sent |= ISCSI_SIGNAL_RX_THREAD;
}
spin_unlock_bh(&ts->ts_state_lock);
return 0;
}
static void iscsi_check_to_add_additional_sets(void)
{
int thread_sets_add;
spin_lock(&inactive_ts_lock);
thread_sets_add = iscsit_global->inactive_ts;
spin_unlock(&inactive_ts_lock);
if (thread_sets_add == 1)
iscsi_allocate_thread_sets(1);
}
static int iscsi_signal_thread_pre_handler(struct iscsi_thread_set *ts)
{
spin_lock_bh(&ts->ts_state_lock);
if ((ts->status == ISCSI_THREAD_SET_DIE) || signal_pending(current)) {
spin_unlock_bh(&ts->ts_state_lock);
return -1;
}
spin_unlock_bh(&ts->ts_state_lock);
return 0;
}
struct iscsi_conn *iscsi_rx_thread_pre_handler(struct iscsi_thread_set *ts)
{
int ret;
spin_lock_bh(&ts->ts_state_lock);
if (ts->create_threads) {
spin_unlock_bh(&ts->ts_state_lock);
goto sleep;
}
flush_signals(current);
if (ts->delay_inactive && (--ts->thread_count == 0)) {
spin_unlock_bh(&ts->ts_state_lock);
iscsi_del_ts_from_active_list(ts);
if (!iscsit_global->in_shutdown)
iscsi_deallocate_extra_thread_sets();
iscsi_add_ts_to_inactive_list(ts);
spin_lock_bh(&ts->ts_state_lock);
}
if ((ts->status == ISCSI_THREAD_SET_RESET) &&
(ts->thread_clear & ISCSI_CLEAR_RX_THREAD))
complete(&ts->rx_restart_comp);
ts->thread_clear &= ~ISCSI_CLEAR_RX_THREAD;
spin_unlock_bh(&ts->ts_state_lock);
sleep:
ret = wait_for_completion_interruptible(&ts->rx_start_comp);
if (ret != 0)
return NULL;
if (iscsi_signal_thread_pre_handler(ts) < 0)
return NULL;
if (!ts->conn) {
pr_err("struct iscsi_thread_set->conn is NULL for"
" thread_id: %d, going back to sleep\n", ts->thread_id);
goto sleep;
}
iscsi_check_to_add_additional_sets();
/*
* The RX Thread starts up the TX Thread and sleeps.
*/
ts->thread_clear |= ISCSI_CLEAR_RX_THREAD;
complete(&ts->tx_start_comp);
wait_for_completion(&ts->tx_post_start_comp);
return ts->conn;
}
struct iscsi_conn *iscsi_tx_thread_pre_handler(struct iscsi_thread_set *ts)
{
int ret;
spin_lock_bh(&ts->ts_state_lock);
if (ts->create_threads) {
spin_unlock_bh(&ts->ts_state_lock);
goto sleep;
}
flush_signals(current);
if (ts->delay_inactive && (--ts->thread_count == 0)) {
spin_unlock_bh(&ts->ts_state_lock);
iscsi_del_ts_from_active_list(ts);
if (!iscsit_global->in_shutdown)
iscsi_deallocate_extra_thread_sets();
iscsi_add_ts_to_inactive_list(ts);
spin_lock_bh(&ts->ts_state_lock);
}
if ((ts->status == ISCSI_THREAD_SET_RESET) &&
(ts->thread_clear & ISCSI_CLEAR_TX_THREAD))
complete(&ts->tx_restart_comp);
ts->thread_clear &= ~ISCSI_CLEAR_TX_THREAD;
spin_unlock_bh(&ts->ts_state_lock);
sleep:
ret = wait_for_completion_interruptible(&ts->tx_start_comp);
if (ret != 0)
return NULL;
if (iscsi_signal_thread_pre_handler(ts) < 0)
return NULL;
if (!ts->conn) {
pr_err("struct iscsi_thread_set->conn is NULL for "
" thread_id: %d, going back to sleep\n",
ts->thread_id);
goto sleep;
}
iscsi_check_to_add_additional_sets();
/*
* From the TX thread, up the tx_post_start_comp that the RX Thread is
* sleeping on in iscsi_rx_thread_pre_handler(), then up the
* rx_post_start_comp that iscsi_activate_thread_set() is sleeping on.
*/
ts->thread_clear |= ISCSI_CLEAR_TX_THREAD;
complete(&ts->tx_post_start_comp);
complete(&ts->rx_post_start_comp);
spin_lock_bh(&ts->ts_state_lock);
ts->status = ISCSI_THREAD_SET_ACTIVE;
spin_unlock_bh(&ts->ts_state_lock);
return ts->conn;
}
int iscsi_thread_set_init(void)
{
int size;
iscsit_global->ts_bitmap_count = ISCSI_TS_BITMAP_BITS;
size = BITS_TO_LONGS(iscsit_global->ts_bitmap_count) * sizeof(long);
iscsit_global->ts_bitmap = kzalloc(size, GFP_KERNEL);
if (!iscsit_global->ts_bitmap) {
pr_err("Unable to allocate iscsit_global->ts_bitmap\n");
return -ENOMEM;
}
return 0;
}
void iscsi_thread_set_free(void)
{
kfree(iscsit_global->ts_bitmap);
}
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