linux-toradex.git/kernel/padata.c, branch v4.4.106

padata: free correct variable

2017-05-20T12:27:02+00:00

commit 07a77929ba672d93642a56dc2255dd21e6e2290b upstream.

The author meant to free the variable that was just allocated, instead
of the one that failed to be allocated, but made a simple typo. This
patch rectifies that.

Signed-off-by: Jason A. Donenfeld 
Signed-off-by: Herbert Xu 
Signed-off-by: Greg Kroah-Hartman

padata: avoid race in reordering

2017-04-08T07:53:32+00:00

commit de5540d088fe97ad583cc7d396586437b32149a5 upstream.

Under extremely heavy uses of padata, crashes occur, and with list
debugging turned on, this happens instead:

[87487.298728] WARNING: CPU: 1 PID: 882 at lib/list_debug.c:33
__list_add+0xae/0x130
[87487.301868] list_add corruption. prev->next should be next
(ffffb17abfc043d0), but was ffff8dba70872c80. (prev=ffff8dba70872b00).
[87487.339011]  [] dump_stack+0x68/0xa3
[87487.342198]  [] ? console_unlock+0x281/0x6d0
[87487.345364]  [] __warn+0xff/0x140
[87487.348513]  [] warn_slowpath_fmt+0x4a/0x50
[87487.351659]  [] __list_add+0xae/0x130
[87487.354772]  [] ? _raw_spin_lock+0x64/0x70
[87487.357915]  [] padata_reorder+0x1e6/0x420
[87487.361084]  [] padata_do_serial+0xa5/0x120

padata_reorder calls list_add_tail with the list to which its adding
locked, which seems correct:

spin_lock(&squeue->serial.lock);
list_add_tail(&padata->list, &squeue->serial.list);
spin_unlock(&squeue->serial.lock);

This therefore leaves only place where such inconsistency could occur:
if padata->list is added at the same time on two different threads.
This pdata pointer comes from the function call to
padata_get_next(pd), which has in it the following block:

next_queue = per_cpu_ptr(pd->pqueue, cpu);
padata = NULL;
reorder = &next_queue->reorder;
if (!list_empty(&reorder->list)) {
       padata = list_entry(reorder->list.next,
                           struct padata_priv, list);
       spin_lock(&reorder->lock);
       list_del_init(&padata->list);
       atomic_dec(&pd->reorder_objects);
       spin_unlock(&reorder->lock);

       pd->processed++;

       goto out;
}
out:
return padata;

I strongly suspect that the problem here is that two threads can race
on reorder list. Even though the deletion is locked, call to
list_entry is not locked, which means it's feasible that two threads
pick up the same padata object and subsequently call list_add_tail on
them at the same time. The fix is thus be hoist that lock outside of
that block.

Signed-off-by: Jason A. Donenfeld 
Acked-by: Steffen Klassert 
Signed-off-by: Herbert Xu 
Signed-off-by: Greg Kroah-Hartman

padata: use %*pb[l] to print bitmaps including cpumasks and nodemasks

2015-02-14T05:21:38+00:00

printk and friends can now format bitmaps using '%*pb[l]'.  cpumask
and nodemask also provide cpumask_pr_args() and nodemask_pr_args()
respectively which can be used to generate the two printf arguments
necessary to format the specified cpu/nodemask.

Signed-off-by: Tejun Heo 
Cc: Steffen Klassert 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

padata: Fix wrong usage of rcu_dereference()

2013-12-05T13:28:42+00:00

A kernel with enabled lockdep complains about the wrong usage of
rcu_dereference() under a rcu_read_lock_bh() protected region.

  ===============================
  [ INFO: suspicious RCU usage. ]
  3.13.0-rc1+ #126 Not tainted
  -------------------------------
  linux/kernel/padata.c:115 suspicious rcu_dereference_check() usage!

  other info that might help us debug this:

  rcu_scheduler_active = 1, debug_locks = 1
  1 lock held by cryptomgr_test/153:
   #0:  (rcu_read_lock_bh){.+....}, at: [] padata_do_parallel+0x5/0x270

Fix that by using rcu_dereference_bh() instead.

Signed-off-by: Mathias Krause 
Acked-by: Steffen Klassert 
Signed-off-by: Herbert Xu

padata: make the sequence counter an atomic_t

2013-10-30T04:02:58+00:00

Using a spinlock to atomically increase a counter sounds wrong -- we've
atomic_t for this!

Also move 'seq_nr' to a different cache line than 'lock' to reduce cache
line trashing. This has the nice side effect of decreasing the size of
struct parallel_data from 192 to 128 bytes for a x86-64 build, e.g.
occupying only two instead of three cache lines.

Those changes results in a 5% performance increase on an IPsec test run
using pcrypt.

Btw. the seq_lock spinlock was never explicitly initialized -- one more
reason to get rid of it.

Signed-off-by: Mathias Krause 
Acked-by: Steffen Klassert 
Signed-off-by: Herbert Xu

padata - Register hotcpu notifier after initialization

2013-08-29T04:37:59+00:00

padata_cpu_callback() takes pinst->lock, to avoid taking
an uninitialized lock, register the notifier after it's
initialization.

Signed-off-by: Richard Weinberger 
Acked-by: Steffen Klassert 
Signed-off-by: Herbert Xu

padata - share code between CPU_ONLINE and CPU_DOWN_FAILED, same to CPU_DOWN_PREPARE and CPU_UP_CANCELED

2013-08-29T04:37:59+00:00

Share code between CPU_ONLINE and CPU_DOWN_FAILED, same to
CPU_DOWN_PREPARE and CPU_UP_CANCELED.

It will fix 2 bugs:

  "not check the return value of __padata_remove_cpu() and __padata_add_cpu()".
  "need add 'break' between CPU_UP_CANCELED and CPU_DOWN_FAILED".

Signed-off-by: Chen Gang 
Acked-by: Steffen Klassert 
Signed-off-by: Herbert Xu

padata: use __this_cpu_read per-cpu helper

2012-12-06T09:16:23+00:00

For bottom halves off, __this_cpu_read is better.

Signed-off-by: Shan Wei 
Reviewed-by: Christoph Lameter 
Acked-by: Steffen Klassert 
Signed-off-by: Herbert Xu

padata: Fix cpu hotplug

2012-03-29T11:52:46+00:00

We don't remove the cpu that went offline from our cpumasks
on cpu hotplug. This got lost somewhere along the line, so
restore it. This fixes a hang of the padata instance on cpu
hotplug.

Signed-off-by: Steffen Klassert 
Signed-off-by: Herbert Xu

padata: Use the online cpumask as the default

2012-03-29T11:52:46+00:00

We use the active cpumask to determine the superset of cpus
to use for parallelization. However, the active cpumask is
for internal usage of the scheduler and therefore not the
appropriate cpumask for these purposes. So use the online
cpumask instead.

Reported-by: Peter Zijlstra 
Signed-off-by: Steffen Klassert 
Signed-off-by: Herbert Xu