* [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL
@ 2020-07-17 10:18 Alberto Milone
2020-07-17 10:43 ` Sebastian Andrzej Siewior
0 siblings, 1 reply; 9+ messages in thread
From: Alberto Milone @ 2020-07-17 10:18 UTC (permalink / raw)
To: linux-fsdevel; +Cc: mingo, bigeasy
Commit cfa6705d89b6 ("radix-tree: Use local_lock
for protection") replaced a DEFINE_PER_CPU() with an
EXPORT_PER_CPU_SYMBOL_GPL(), which made the
radix_tree_preloads symbol GPL only. All the other
symbols in the file are exported with EXPORT_SYMBOL().
The change breaks the NVIDIA 390 legacy driver.
This commit uses EXPORT_PER_CPU_SYMBOL() for
radix_tree_preloads.
Signed-off-by: Alberto Milone <alberto.milone@canonical.com>
---
lib/radix-tree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 34e406fe561f..5f3ec9be6e37 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -61,7 +61,7 @@ struct kmem_cache *radix_tree_node_cachep;
DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = {
.lock = INIT_LOCAL_LOCK(lock),
};
-EXPORT_PER_CPU_SYMBOL_GPL(radix_tree_preloads);
+EXPORT_PER_CPU_SYMBOL(radix_tree_preloads);
static inline struct radix_tree_node *entry_to_node(void *ptr)
{
--
2.25.1
^ permalink raw reply related [flat|nested] 9+ messages in thread
* Re: [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL
2020-07-17 10:18 [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL Alberto Milone
@ 2020-07-17 10:43 ` Sebastian Andrzej Siewior
[not found] ` <ba5d59f6-2e40-d13a-ecc8-d8430a1b6a14@canonical.com>
0 siblings, 1 reply; 9+ messages in thread
From: Sebastian Andrzej Siewior @ 2020-07-17 10:43 UTC (permalink / raw)
To: Alberto Milone; +Cc: linux-fsdevel, mingo
On 2020-07-17 12:18:48 [+0200], Alberto Milone wrote:
> Commit cfa6705d89b6 ("radix-tree: Use local_lock
> for protection") replaced a DEFINE_PER_CPU() with an
> EXPORT_PER_CPU_SYMBOL_GPL(), which made the
> radix_tree_preloads symbol GPL only. All the other
> symbols in the file are exported with EXPORT_SYMBOL().
Is this a problem if you disable CONFIG_DEBUG_LOCK_ALLOC ?
> The change breaks the NVIDIA 390 legacy driver.
>
> This commit uses EXPORT_PER_CPU_SYMBOL() for
> radix_tree_preloads.
>
Sebastian
^ permalink raw reply [flat|nested] 9+ messages in thread
* Fwd: [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL
[not found] ` <ba5d59f6-2e40-d13a-ecc8-d8430a1b6a14@canonical.com>
@ 2020-07-17 12:35 ` Alberto Milone
2020-07-17 13:21 ` Sebastian Andrzej Siewior
1 sibling, 0 replies; 9+ messages in thread
From: Alberto Milone @ 2020-07-17 12:35 UTC (permalink / raw)
To: linux-fsdevel
-------- Forwarded Message --------
Subject: Re: [PATCH 1/1] radix-tree: do not export radix_tree_preloads
as GPL
Date: Fri, 17 Jul 2020 14:33:31 +0200
From: Alberto Milone <alberto.milone@canonical.com>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
CC: linux-fsdevel@vger.kernel.org, mingo@kernel.org
On 17/07/2020 12:43, Sebastian Andrzej Siewior wrote:
> On 2020-07-17 12:18:48 [+0200], Alberto Milone wrote:
>> Commit cfa6705d89b6 ("radix-tree: Use local_lock
>> for protection") replaced a DEFINE_PER_CPU() with an
>> EXPORT_PER_CPU_SYMBOL_GPL(), which made the
>> radix_tree_preloads symbol GPL only. All the other
>> symbols in the file are exported with EXPORT_SYMBOL().
> Is this a problem if you disable CONFIG_DEBUG_LOCK_ALLOC ?
I checked and CONFIG_DEBUG_LOCK_ALLOC is not enabled in our kernels.
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL
[not found] ` <ba5d59f6-2e40-d13a-ecc8-d8430a1b6a14@canonical.com>
2020-07-17 12:35 ` Fwd: " Alberto Milone
@ 2020-07-17 13:21 ` Sebastian Andrzej Siewior
2020-07-17 13:45 ` Alberto Milone
1 sibling, 1 reply; 9+ messages in thread
From: Sebastian Andrzej Siewior @ 2020-07-17 13:21 UTC (permalink / raw)
To: Alberto Milone; +Cc: linux-fsdevel, mingo
On 2020-07-17 14:33:31 [+0200], Alberto Milone wrote:
>
> I checked and CONFIG_DEBUG_LOCK_ALLOC is not enabled in our kernels.
The access to that variable is optimized away if not for debug. I made
this:
| #include <linux/module.h>
| #include <linux/idr.h>
|
| static int le_init(void)
| {
| idr_preload_end();
| return 0;
| }
| module_init(le_init);
|
| static void le_exit(void)
| {
| }
| module_exit(le_exit);
|
| MODULE_DESCRIPTION("driver");
| MODULE_LICENSE("prop");
and it produced a .ko. Here the "idr_preload_end()" was reduced to
"preempt_enable()" as intended. No access to
"&radix_tree_preloads.lock".
Sebastian
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL
2020-07-17 13:21 ` Sebastian Andrzej Siewior
@ 2020-07-17 13:45 ` Alberto Milone
2020-07-17 14:28 ` Seth Forshee
0 siblings, 1 reply; 9+ messages in thread
From: Alberto Milone @ 2020-07-17 13:45 UTC (permalink / raw)
To: Sebastian Andrzej Siewior; +Cc: linux-fsdevel, mingo, Seth Forshee
On 17/07/2020 15:21, Sebastian Andrzej Siewior wrote:
> On 2020-07-17 14:33:31 [+0200], Alberto Milone wrote:
>> I checked and CONFIG_DEBUG_LOCK_ALLOC is not enabled in our kernels.
> The access to that variable is optimized away if not for debug. I made
> this:
> | #include <linux/module.h>
> | #include <linux/idr.h>
> |
> | static int le_init(void)
> | {
> | idr_preload_end();
> | return 0;
> | }
> | module_init(le_init);
> |
> | static void le_exit(void)
> | {
> | }
> | module_exit(le_exit);
> |
> | MODULE_DESCRIPTION("driver");
> | MODULE_LICENSE("prop");
>
> and it produced a .ko. Here the "idr_preload_end()" was reduced to
> "preempt_enable()" as intended. No access to
> "&radix_tree_preloads.lock".
>
> Sebastian
* Subscribing Seth
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL
2020-07-17 13:45 ` Alberto Milone
@ 2020-07-17 14:28 ` Seth Forshee
2020-07-17 14:31 ` Sebastian Andrzej Siewior
2020-07-17 14:34 ` Seth Forshee
0 siblings, 2 replies; 9+ messages in thread
From: Seth Forshee @ 2020-07-17 14:28 UTC (permalink / raw)
To: Alberto Milone; +Cc: Sebastian Andrzej Siewior, linux-fsdevel, mingo
On Fri, Jul 17, 2020 at 03:45:10PM +0200, Alberto Milone wrote:
> On 17/07/2020 15:21, Sebastian Andrzej Siewior wrote:
> > On 2020-07-17 14:33:31 [+0200], Alberto Milone wrote:
> >> I checked and CONFIG_DEBUG_LOCK_ALLOC is not enabled in our kernels.
> > The access to that variable is optimized away if not for debug. I made
> > this:
> > | #include <linux/module.h>
> > | #include <linux/idr.h>
> > |
> > | static int le_init(void)
> > | {
> > | idr_preload_end();
> > | return 0;
> > | }
> > | module_init(le_init);
> > |
> > | static void le_exit(void)
> > | {
> > | }
> > | module_exit(le_exit);
> > |
> > | MODULE_DESCRIPTION("driver");
> > | MODULE_LICENSE("prop");
> >
> > and it produced a .ko. Here the "idr_preload_end()" was reduced to
> > "preempt_enable()" as intended. No access to
> > "&radix_tree_preloads.lock".
> >
> > Sebastian
> * Subscribing Seth
Looks like the driver is not using idr_preload_end() though, it is
calling radix_tree_preload_end() which uses radix_tree_preloads whether
or not CONFIG_DEBUG_LOCK_ALLOC is enabled.
Thanks,
Seth
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL
2020-07-17 14:28 ` Seth Forshee
@ 2020-07-17 14:31 ` Sebastian Andrzej Siewior
2020-07-17 14:34 ` Seth Forshee
1 sibling, 0 replies; 9+ messages in thread
From: Sebastian Andrzej Siewior @ 2020-07-17 14:31 UTC (permalink / raw)
To: Seth Forshee; +Cc: Alberto Milone, linux-fsdevel, mingo
On 2020-07-17 09:28:48 [-0500], Seth Forshee wrote:
>
> Looks like the driver is not using idr_preload_end() though, it is
> calling radix_tree_preload_end() which uses radix_tree_preloads whether
> or not CONFIG_DEBUG_LOCK_ALLOC is enabled.
static inline void radix_tree_preload_end(void)
{
local_unlock(&radix_tree_preloads.lock);
}
=>
#define local_unlock(lock) __local_unlock(lock)
=>
#define __local_unlock(lock) \
do { \
local_lock_release(this_cpu_ptr(lock)); \
preempt_enable(); \
} while (0)
=>
static inline void local_lock_release(local_lock_t *l) { }
> Thanks,
> Seth
Sebastian
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL
2020-07-17 14:28 ` Seth Forshee
2020-07-17 14:31 ` Sebastian Andrzej Siewior
@ 2020-07-17 14:34 ` Seth Forshee
[not found] ` <20200717155519.GM3644@ubuntu-x1>
1 sibling, 1 reply; 9+ messages in thread
From: Seth Forshee @ 2020-07-17 14:34 UTC (permalink / raw)
To: Alberto Milone; +Cc: Sebastian Andrzej Siewior, linux-fsdevel, mingo
On Fri, Jul 17, 2020 at 09:28:48AM -0500, Seth Forshee wrote:
> On Fri, Jul 17, 2020 at 03:45:10PM +0200, Alberto Milone wrote:
> > On 17/07/2020 15:21, Sebastian Andrzej Siewior wrote:
> > > On 2020-07-17 14:33:31 [+0200], Alberto Milone wrote:
> > >> I checked and CONFIG_DEBUG_LOCK_ALLOC is not enabled in our kernels.
> > > The access to that variable is optimized away if not for debug. I made
> > > this:
> > > | #include <linux/module.h>
> > > | #include <linux/idr.h>
> > > |
> > > | static int le_init(void)
> > > | {
> > > | idr_preload_end();
> > > | return 0;
> > > | }
> > > | module_init(le_init);
> > > |
> > > | static void le_exit(void)
> > > | {
> > > | }
> > > | module_exit(le_exit);
> > > |
> > > | MODULE_DESCRIPTION("driver");
> > > | MODULE_LICENSE("prop");
> > >
> > > and it produced a .ko. Here the "idr_preload_end()" was reduced to
> > > "preempt_enable()" as intended. No access to
> > > "&radix_tree_preloads.lock".
> > >
> > > Sebastian
> > * Subscribing Seth
>
> Looks like the driver is not using idr_preload_end() though, it is
> calling radix_tree_preload_end() which uses radix_tree_preloads whether
> or not CONFIG_DEBUG_LOCK_ALLOC is enabled.
Sorry, I didn't dig deep enough. I see that radix_tree_preload_end() is
expected to opimize away that access too. I wonder if different
toolchains could be ending up with different reults.
Seth
^ permalink raw reply [flat|nested] 9+ messages in thread
* Re: [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL
[not found] ` <20200717155519.GM3644@ubuntu-x1>
@ 2020-07-20 14:49 ` Seth Forshee
0 siblings, 0 replies; 9+ messages in thread
From: Seth Forshee @ 2020-07-20 14:49 UTC (permalink / raw)
To: Sebastian Andrzej Siewior; +Cc: Alberto Milone, linux-fsdevel, mingo
On Fri, Jul 17, 2020 at 10:55:19AM -0500, Seth Forshee wrote:
> On Fri, Jul 17, 2020 at 09:34:39AM -0500, Seth Forshee wrote:
> > On Fri, Jul 17, 2020 at 09:28:48AM -0500, Seth Forshee wrote:
> > > On Fri, Jul 17, 2020 at 03:45:10PM +0200, Alberto Milone wrote:
> > > > On 17/07/2020 15:21, Sebastian Andrzej Siewior wrote:
> > > > > On 2020-07-17 14:33:31 [+0200], Alberto Milone wrote:
> > > > >> I checked and CONFIG_DEBUG_LOCK_ALLOC is not enabled in our kernels.
> > > > > The access to that variable is optimized away if not for debug. I made
> > > > > this:
> > > > > | #include <linux/module.h>
> > > > > | #include <linux/idr.h>
> > > > > |
> > > > > | static int le_init(void)
> > > > > | {
> > > > > | idr_preload_end();
> > > > > | return 0;
> > > > > | }
> > > > > | module_init(le_init);
> > > > > |
> > > > > | static void le_exit(void)
> > > > > | {
> > > > > | }
> > > > > | module_exit(le_exit);
> > > > > |
> > > > > | MODULE_DESCRIPTION("driver");
> > > > > | MODULE_LICENSE("prop");
> > > > >
> > > > > and it produced a .ko. Here the "idr_preload_end()" was reduced to
> > > > > "preempt_enable()" as intended. No access to
> > > > > "&radix_tree_preloads.lock".
> > > > >
> > > > > Sebastian
> > > > * Subscribing Seth
> > >
> > > Looks like the driver is not using idr_preload_end() though, it is
> > > calling radix_tree_preload_end() which uses radix_tree_preloads whether
> > > or not CONFIG_DEBUG_LOCK_ALLOC is enabled.
> >
> > Sorry, I didn't dig deep enough. I see that radix_tree_preload_end() is
> > expected to opimize away that access too. I wonder if different
> > toolchains could be ending up with different reults.
>
> Your example gives me the same error about using radix_tree_preloads. I
> also added:
>
> #ifdef CONFIG_DEBUG_LOCK_ALLOC
> #warn "CONFIG_DEBUG_LOCK_ALLOC enabled"
> #endif
>
> Nothing is printed, so the option really does appear to be off. I've
> been staring at it a while and I can't see why the module still ends up
> referencing radix_tree_preloads, but it is clearly happening.
Even ignoring what is happening with our kernels, isn't this a
regression with CONFIG_DEBUG_LOCK_ALLOC=y that should be fixed? There
have been similar cases in the past where gpl-only exports leaked out
into interfaces which were previously usable by non-gpl modules, and
they were fixed -- 31c5bda3a656089f01963d290a40ccda181f816e and
9e987b70ada27554c5d176421de1d167218c49b5 are a couple of examples I was
able to find with minimal effort. Why is this case any different?
Thanks,
Seth
^ permalink raw reply [flat|nested] 9+ messages in thread
end of thread, other threads:[~2020-07-20 14:49 UTC | newest]
Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-07-17 10:18 [PATCH 1/1] radix-tree: do not export radix_tree_preloads as GPL Alberto Milone
2020-07-17 10:43 ` Sebastian Andrzej Siewior
[not found] ` <ba5d59f6-2e40-d13a-ecc8-d8430a1b6a14@canonical.com>
2020-07-17 12:35 ` Fwd: " Alberto Milone
2020-07-17 13:21 ` Sebastian Andrzej Siewior
2020-07-17 13:45 ` Alberto Milone
2020-07-17 14:28 ` Seth Forshee
2020-07-17 14:31 ` Sebastian Andrzej Siewior
2020-07-17 14:34 ` Seth Forshee
[not found] ` <20200717155519.GM3644@ubuntu-x1>
2020-07-20 14:49 ` Seth Forshee
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