[ANNOUNCE] v5.6.19-rt12

From: Sebastian Andrzej Siewior
Date: Thu Aug 20 2020 - 10:30:40 EST

Dear RT folks!

I'm pleased to announce the v5.6.19-rt12 patch set.

Changes since v5.6.19-rt11:

- Use a raw_spinlock_t in io-wq. This avoids acquiring a sleeping lock
in atomic context.

- Address ifnullfree.cocci warnings in printk. Patch by Julia Lawall.

- Add "dev: Defer free of skbs in flush_backlog" from upstream.

- As a result of the previous patch, the "skbufhead-raw-lock.patch"
can be shrunken by removing the now no longer required
softnet_data::tofree_queue and the special IRQ-off handling.

Known issues
- It has been pointed out that due to changes to the printk code the
internal buffer representation changed. This is only an issue if tools
like `crash' are used to extract the printk buffer from a kernel memory
image.

The delta patch against v5.6.19-rt11 is appended below and can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.6/incr/patch-5.6.19-rt11-rt12.patch.xz

You can get this release via the git tree at:

git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git v5.6.19-rt12

The RT patch against v5.6.19 can be found here:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.6/older/patch-5.6.19-rt12.patch.xz

The split quilt queue is available at:

https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.6/older/patches-5.6.19-rt12.tar.xz

Sebastian

diff --git a/fs/io-wq.c b/fs/io-wq.c
index 5cef075c0b379..4a7cbf46213e9 100644
--- a/fs/io-wq.c
+++ b/fs/io-wq.c
@@ -85,7 +85,7 @@ enum {
*/
struct io_wqe {
struct {
- spinlock_t lock;
+ raw_spinlock_t lock;
struct io_wq_work_list work_list;
unsigned long hash_map;
unsigned flags;
@@ -145,7 +145,7 @@ static bool __io_worker_unuse(struct io_wqe *wqe, struct io_worker *worker)

if (current->files != worker->restore_files) {
__acquire(&wqe->lock);
- spin_unlock_irq(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);
dropped_lock = true;

task_lock(current);
@@ -163,7 +163,7 @@ static bool __io_worker_unuse(struct io_wqe *wqe, struct io_worker *worker)
if (worker->mm) {
if (!dropped_lock) {
__acquire(&wqe->lock);
- spin_unlock_irq(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);
dropped_lock = true;
}
__set_current_state(TASK_RUNNING);
@@ -218,17 +218,17 @@ static void io_worker_exit(struct io_worker *worker)
worker->flags = 0;
preempt_enable();

- spin_lock_irq(&wqe->lock);
+ raw_spin_lock_irq(&wqe->lock);
hlist_nulls_del_rcu(&worker->nulls_node);
list_del_rcu(&worker->all_list);
if (__io_worker_unuse(wqe, worker)) {
__release(&wqe->lock);
- spin_lock_irq(&wqe->lock);
+ raw_spin_lock_irq(&wqe->lock);
}
acct->nr_workers--;
nr_workers = wqe->acct[IO_WQ_ACCT_BOUND].nr_workers +
wqe->acct[IO_WQ_ACCT_UNBOUND].nr_workers;
- spin_unlock_irq(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);

/* all workers gone, wq exit can proceed */
if (!nr_workers && refcount_dec_and_test(&wqe->wq->refs))
@@ -463,7 +463,7 @@ static void io_worker_handle_work(struct io_worker *worker)
else if (!wq_list_empty(&wqe->work_list))
wqe->flags |= IO_WQE_FLAG_STALLED;

- spin_unlock_irq(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);
if (put_work && wq->put_work)
wq->put_work(old_work);
if (!work)
@@ -514,14 +514,14 @@ static void io_worker_handle_work(struct io_worker *worker)
worker->cur_work = NULL;
spin_unlock_irq(&worker->lock);

- spin_lock_irq(&wqe->lock);
+ raw_spin_lock_irq(&wqe->lock);

if (hash != -1U) {
wqe->hash_map &= ~BIT_ULL(hash);
wqe->flags &= ~IO_WQE_FLAG_STALLED;
}
if (work && work != old_work) {
- spin_unlock_irq(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);

if (put_work && wq->put_work) {
wq->put_work(put_work);
@@ -546,7 +546,7 @@ static int io_wqe_worker(void *data)
while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
set_current_state(TASK_INTERRUPTIBLE);
loop:
- spin_lock_irq(&wqe->lock);
+ raw_spin_lock_irq(&wqe->lock);
if (io_wqe_run_queue(wqe)) {
__set_current_state(TASK_RUNNING);
io_worker_handle_work(worker);
@@ -557,7 +557,7 @@ static int io_wqe_worker(void *data)
__release(&wqe->lock);
goto loop;
}
- spin_unlock_irq(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);
if (signal_pending(current))
flush_signals(current);
if (schedule_timeout(WORKER_IDLE_TIMEOUT))
@@ -569,11 +569,11 @@ static int io_wqe_worker(void *data)
}

if (test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
- spin_lock_irq(&wqe->lock);
+ raw_spin_lock_irq(&wqe->lock);
if (!wq_list_empty(&wqe->work_list))
io_worker_handle_work(worker);
else
- spin_unlock_irq(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);
}

io_worker_exit(worker);
@@ -613,9 +613,9 @@ void io_wq_worker_sleeping(struct task_struct *tsk)

worker->flags &= ~IO_WORKER_F_RUNNING;

- spin_lock_irq(&wqe->lock);
+ raw_spin_lock_irq(&wqe->lock);
io_wqe_dec_running(wqe, worker);
- spin_unlock_irq(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);
}

static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
@@ -639,7 +639,7 @@ static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
return false;
}

- spin_lock_irq(&wqe->lock);
+ raw_spin_lock_irq(&wqe->lock);
hlist_nulls_add_head_rcu(&worker->nulls_node, &wqe->free_list);
list_add_tail_rcu(&worker->all_list, &wqe->all_list);
worker->flags |= IO_WORKER_F_FREE;
@@ -648,7 +648,7 @@ static bool create_io_worker(struct io_wq *wq, struct io_wqe *wqe, int index)
if (!acct->nr_workers && (worker->flags & IO_WORKER_F_BOUND))
worker->flags |= IO_WORKER_F_FIXED;
acct->nr_workers++;
- spin_unlock_irq(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);

if (index == IO_WQ_ACCT_UNBOUND)
atomic_inc(&wq->user->processes);
@@ -700,12 +700,12 @@ static int io_wq_manager(void *data)
if (!node_online(node))
continue;

- spin_lock_irq(&wqe->lock);
+ raw_spin_lock_irq(&wqe->lock);
if (io_wqe_need_worker(wqe, IO_WQ_ACCT_BOUND))
fork_worker[IO_WQ_ACCT_BOUND] = true;
if (io_wqe_need_worker(wqe, IO_WQ_ACCT_UNBOUND))
fork_worker[IO_WQ_ACCT_UNBOUND] = true;
- spin_unlock_irq(&wqe->lock);
+ raw_spin_unlock_irq(&wqe->lock);
if (fork_worker[IO_WQ_ACCT_BOUND])
create_io_worker(wq, wqe, IO_WQ_ACCT_BOUND);
if (fork_worker[IO_WQ_ACCT_UNBOUND])
@@ -776,10 +776,10 @@ static void io_wqe_enqueue(struct io_wqe *wqe, struct io_wq_work *work)
}

work_flags = work->flags;
- spin_lock_irqsave(&wqe->lock, flags);
+ raw_spin_lock_irqsave(&wqe->lock, flags);
wq_list_add_tail(&work->list, &wqe->work_list);
wqe->flags &= ~IO_WQE_FLAG_STALLED;
- spin_unlock_irqrestore(&wqe->lock, flags);
+ raw_spin_unlock_irqrestore(&wqe->lock, flags);

if ((work_flags & IO_WQ_WORK_CONCURRENT) ||
!atomic_read(&acct->nr_running))
@@ -897,7 +897,7 @@ static enum io_wq_cancel io_wqe_cancel_cb_work(struct io_wqe *wqe,
unsigned long flags;
bool found = false;

- spin_lock_irqsave(&wqe->lock, flags);
+ raw_spin_lock_irqsave(&wqe->lock, flags);
wq_list_for_each(node, prev, &wqe->work_list) {
work = container_of(node, struct io_wq_work, list);

@@ -907,7 +907,7 @@ static enum io_wq_cancel io_wqe_cancel_cb_work(struct io_wqe *wqe,
break;
}
}
- spin_unlock_irqrestore(&wqe->lock, flags);
+ raw_spin_unlock_irqrestore(&wqe->lock, flags);

if (found) {
io_run_cancel(work);
@@ -972,7 +972,7 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
* from there. CANCEL_OK means that the work is returned as-new,
* no completion will be posted for it.
*/
- spin_lock_irqsave(&wqe->lock, flags);
+ raw_spin_lock_irqsave(&wqe->lock, flags);
wq_list_for_each(node, prev, &wqe->work_list) {
work = container_of(node, struct io_wq_work, list);

@@ -982,7 +982,7 @@ static enum io_wq_cancel io_wqe_cancel_work(struct io_wqe *wqe,
break;
}
}
- spin_unlock_irqrestore(&wqe->lock, flags);
+ raw_spin_unlock_irqrestore(&wqe->lock, flags);

if (found) {
io_run_cancel(work);
@@ -1097,7 +1097,7 @@ struct io_wq *io_wq_create(unsigned bounded, struct io_wq_data *data)
}
atomic_set(&wqe->acct[IO_WQ_ACCT_UNBOUND].nr_running, 0);
wqe->wq = wq;
- spin_lock_init(&wqe->lock);
+ raw_spin_lock_init(&wqe->lock);
INIT_WQ_LIST(&wqe->work_list);
INIT_HLIST_NULLS_HEAD(&wqe->free_list, 0);
INIT_LIST_HEAD(&wqe->all_list);
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 43240d8534686..6c3f7032e8d9d 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3090,7 +3090,6 @@ struct softnet_data {
unsigned int dropped;
struct sk_buff_head input_pkt_queue;
struct napi_struct backlog;
- struct sk_buff_head tofree_queue;

};

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 6296d348f3008..5a5363877f946 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1458,10 +1458,8 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
if (clear && !seq)
syslog_clear();

- if (text)
- kfree(text);
- if (msgbuf)
- kfree(msgbuf);
+ kfree(text);
+ kfree(msgbuf);
return len;
}

@@ -1614,10 +1612,8 @@ int do_syslog(int type, char __user *buf, int len, int source)
break;
}
out:
- if (msgbuf)
- kfree(msgbuf);
- if (text)
- kfree(text);
+ kfree(msgbuf);
+ kfree(text);
return error;
}

diff --git a/localversion-rt b/localversion-rt
index 05c35cb580779..6e44e540b927b 100644
--- a/localversion-rt
+++ b/localversion-rt
@@ -1 +1 @@
--rt11
+-rt12
diff --git a/net/core/dev.c b/net/core/dev.c
index fbf66f197cf3d..643b81cd42610 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -5507,7 +5507,7 @@ static void flush_backlog(struct work_struct *work)
skb_queue_walk_safe(&sd->input_pkt_queue, skb, tmp) {
if (skb->dev->reg_state == NETREG_UNREGISTERING) {
__skb_unlink(skb, &sd->input_pkt_queue);
- __skb_queue_tail(&sd->tofree_queue, skb);
+ dev_kfree_skb_irq(skb);
input_queue_head_incr(sd);
}
}
@@ -5517,14 +5517,11 @@ static void flush_backlog(struct work_struct *work)
skb_queue_walk_safe(&sd->process_queue, skb, tmp) {
if (skb->dev->reg_state == NETREG_UNREGISTERING) {
__skb_unlink(skb, &sd->process_queue);
- __skb_queue_tail(&sd->tofree_queue, skb);
+ kfree_skb(skb);
input_queue_head_incr(sd);
}
}
- if (!skb_queue_empty(&sd->tofree_queue))
- raise_softirq_irqoff(NET_RX_SOFTIRQ);
local_bh_enable();
-
}

static void flush_all_backlogs(void)
@@ -6145,9 +6142,7 @@ static int process_backlog(struct napi_struct *napi, int quota)
while (again) {
struct sk_buff *skb;

- local_irq_disable();
while ((skb = __skb_dequeue(&sd->process_queue))) {
- local_irq_enable();
rcu_read_lock();
__netif_receive_skb(skb);
rcu_read_unlock();
@@ -6155,9 +6150,9 @@ static int process_backlog(struct napi_struct *napi, int quota)
if (++work >= quota)
return work;

- local_irq_disable();
}

+ local_irq_disable();
rps_lock(sd);
if (skb_queue_empty(&sd->input_pkt_queue)) {
/*
@@ -6639,21 +6634,13 @@ static __latent_entropy void net_rx_action(struct softirq_action *h)
unsigned long time_limit = jiffies +
usecs_to_jiffies(netdev_budget_usecs);
int budget = netdev_budget;
- struct sk_buff_head tofree_q;
- struct sk_buff *skb;
LIST_HEAD(list);
LIST_HEAD(repoll);

- __skb_queue_head_init(&tofree_q);
-
local_irq_disable();
- skb_queue_splice_init(&sd->tofree_queue, &tofree_q);
list_splice_init(&sd->poll_list, &list);
local_irq_enable();

- while ((skb = __skb_dequeue(&tofree_q)))
- kfree_skb(skb);
-
for (;;) {
struct napi_struct *n;

@@ -10205,13 +10192,10 @@ static int dev_cpu_dead(unsigned int oldcpu)
netif_rx_ni(skb);
input_queue_head_incr(oldsd);
}
- while ((skb = __skb_dequeue(&oldsd->input_pkt_queue))) {
+ while ((skb = skb_dequeue(&oldsd->input_pkt_queue))) {
netif_rx_ni(skb);
input_queue_head_incr(oldsd);
}
- while ((skb = __skb_dequeue(&oldsd->tofree_queue))) {
- kfree_skb(skb);
- }

return 0;
}
@@ -10525,8 +10509,7 @@ static int __init net_dev_init(void)
INIT_WORK(flush, flush_backlog);

skb_queue_head_init_raw(&sd->input_pkt_queue);
- skb_queue_head_init_raw(&sd->process_queue);
- skb_queue_head_init_raw(&sd->tofree_queue);
+ skb_queue_head_init(&sd->process_queue);
#ifdef CONFIG_XFRM_OFFLOAD
skb_queue_head_init(&sd->xfrm_backlog);
#endif