[PATCH] checkpatch: Error out if deprecated RCU API used

[PATCH] checkpatch: Error out if deprecated RCU API used

[Joel Fernandes (Google)]

Single-argument kvfree_rcu() usage is being deprecated [1] [2] as it is
error-prone. However, till all users are converted, we would like to introduce
checkpatch errors for new patches submitted.

This patch adds support for the same. Tested with a trial patch.

For now, we are only considering usages that don't have compound
nesting, for example ignore: kvfree_rcu( (rcu_head_obj), rcu_head_name).
This is sufficient as such usages are unlikely.

Once all users are converted and we remove the old API, we can also revert this
checkpatch patch then.

[1] https://lore.kernel.org/rcu/CAEXW_YRhHaVuq+5f+VgCZM=SF+9xO+QXaxe0yE7oA9iCXK-XPg@mail.gmail.com/
[2] https://lore.kernel.org/rcu/CAEXW_YSY=q2_uaE2qo4XSGjzs4+C102YMVJ7kWwuT5LGmJGGew@mail.gmail.com/

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 scripts/checkpatch.pl |  9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index bd44d12965c9..9da0a3cb1615 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -6388,6 +6388,15 @@ sub process {
 			}
 		}
 
+# check for soon-to-be-deprecated single-argument k[v]free_rcu() API
+		if ($line =~ /\bk[v]?free_rcu\s*\([^(]+\)/) {
+			if ($line =~ /\bk[v]?free_rcu\s*\([^,]+\)/) {
+				ERROR("DEPRECATED_API",
+				      "Single-argument k[v]free_rcu() API is deprecated, please call the API with an rcu_head object passed, like: k[v]free_rcu(object_ptr, rcu_head_name);  " . $herecurr);
+			}
+		}
+
+
 # check for unnecessary "Out of Memory" messages
 		if ($line =~ /^\+.*\b$logFunctions\s*\(/ &&
 		    $prevline =~ /^[ \+]\s*if\s*\(\s*(\!\s*|NULL\s*==\s*)?($Lval)(\s*==\s*NULL\s*)?\s*\)/ &&
-- 
2.40.0.rc0.216.gc4246ad0f0-goog

Re: [PATCH] checkpatch: Error out if deprecated RCU API used

[Joe Perches]

On Tue, 2023-03-07 at 03:04 +0000, Joel Fernandes (Google) wrote:
> Single-argument kvfree_rcu() usage is being deprecated [1] [2] as it is
> error-prone. However, till all users are converted, we would like to introduce
> checkpatch errors for new patches submitted.
> 
> This patch adds support for the same. Tested with a trial patch.
> 
> For now, we are only considering usages that don't have compound
> nesting, for example ignore: kvfree_rcu( (rcu_head_obj), rcu_head_name).
> This is sufficient as such usages are unlikely.
> 
> Once all users are converted and we remove the old API, we can also revert this
> checkpatch patch then.

I think this should be added to the deprecated_apis hash instead

our %deprecated_apis = (
	"synchronize_rcu_bh"			=> "synchronize_rcu",
	"synchronize_rcu_bh_expedited"		=> "synchronize_rcu_expedited",
	"call_rcu_bh"				=> "call_rcu",
	"rcu_barrier_bh"			=> "rcu_barrier",
	"synchronize_sched"			=> "synchronize_rcu",
	"synchronize_sched_expedited"		=> "synchronize_rcu_expedited",
	"call_rcu_sched"			=> "call_rcu",
	"rcu_barrier_sched"			=> "rcu_barrier",
	"get_state_synchronize_sched"		=> "get_state_synchronize_rcu",
	"cond_synchronize_sched"		=> "cond_synchronize_rcu",
	"kmap"					=> "kmap_local_page",
	"kunmap"				=> "kunmap_local",
	"kmap_atomic"				=> "kmap_local_page",
	"kunmap_atomic"				=> "kunmap_local",
);

Re: [PATCH] checkpatch: Error out if deprecated RCU API used

[Joel Fernandes]

On Mon, Mar 6, 2023 at 10:08 PM Joe Perches <joe@perches.com> wrote:
>
> On Tue, 2023-03-07 at 03:04 +0000, Joel Fernandes (Google) wrote:
> > Single-argument kvfree_rcu() usage is being deprecated [1] [2] as it is
> > error-prone. However, till all users are converted, we would like to introduce
> > checkpatch errors for new patches submitted.
> >
> > This patch adds support for the same. Tested with a trial patch.
> >
> > For now, we are only considering usages that don't have compound
> > nesting, for example ignore: kvfree_rcu( (rcu_head_obj), rcu_head_name).
> > This is sufficient as such usages are unlikely.
> >
> > Once all users are converted and we remove the old API, we can also revert this
> > checkpatch patch then.
>
> I think this should be added to the deprecated_apis hash instead
>
> our %deprecated_apis = (
>         "synchronize_rcu_bh"                    => "synchronize_rcu",
>         "synchronize_rcu_bh_expedited"          => "synchronize_rcu_expedited",
>         "call_rcu_bh"                           => "call_rcu",
>         "rcu_barrier_bh"                        => "rcu_barrier",
>         "synchronize_sched"                     => "synchronize_rcu",
>         "synchronize_sched_expedited"           => "synchronize_rcu_expedited",
>         "call_rcu_sched"                        => "call_rcu",
>         "rcu_barrier_sched"                     => "rcu_barrier",
>         "get_state_synchronize_sched"           => "get_state_synchronize_rcu",
>         "cond_synchronize_sched"                => "cond_synchronize_rcu",
>         "kmap"                                  => "kmap_local_page",
>         "kunmap"                                => "kunmap_local",
>         "kmap_atomic"                           => "kmap_local_page",
>         "kunmap_atomic"                         => "kunmap_local",
> );

This is not an API name change though, it is a "number of arguments"
or argument list change. Is there a different way to do it?

thanks,

 - Joel

Re: [PATCH] checkpatch: Error out if deprecated RCU API used

[Joe Perches]

On Mon, 2023-03-06 at 22:10 -0500, Joel Fernandes wrote:
> On Mon, Mar 6, 2023 at 10:08 PM Joe Perches <joe@perches.com> wrote:
> > 
> > On Tue, 2023-03-07 at 03:04 +0000, Joel Fernandes (Google) wrote:
> > > Single-argument kvfree_rcu() usage is being deprecated [1] [2] as it is
> > > error-prone. However, till all users are converted, we would like to introduce
> > > checkpatch errors for new patches submitted.
> > > 
> > > This patch adds support for the same. Tested with a trial patch.
> > > 
> > > For now, we are only considering usages that don't have compound
> > > nesting, for example ignore: kvfree_rcu( (rcu_head_obj), rcu_head_name).
> > > This is sufficient as such usages are unlikely.
> > > 
> > > Once all users are converted and we remove the old API, we can also revert this
> > > checkpatch patch then.
> > 
> > I think this should be added to the deprecated_apis hash instead
> > 
> > our %deprecated_apis = (
> >         "synchronize_rcu_bh"                    => "synchronize_rcu",
> >         "synchronize_rcu_bh_expedited"          => "synchronize_rcu_expedited",
> >         "call_rcu_bh"                           => "call_rcu",
> >         "rcu_barrier_bh"                        => "rcu_barrier",
> >         "synchronize_sched"                     => "synchronize_rcu",
> >         "synchronize_sched_expedited"           => "synchronize_rcu_expedited",
> >         "call_rcu_sched"                        => "call_rcu",
> >         "rcu_barrier_sched"                     => "rcu_barrier",
> >         "get_state_synchronize_sched"           => "get_state_synchronize_rcu",
> >         "cond_synchronize_sched"                => "cond_synchronize_rcu",
> >         "kmap"                                  => "kmap_local_page",
> >         "kunmap"                                => "kunmap_local",
> >         "kmap_atomic"                           => "kmap_local_page",
> >         "kunmap_atomic"                         => "kunmap_local",
> > );
> 
> This is not an API name change though, it is a "number of arguments"
> or argument list change. Is there a different way to do it?

Ah, no, not really.

btw: I don't see a single use of this call without a comma in the tree.

Re: [PATCH] checkpatch: Error out if deprecated RCU API used

[Joel Fernandes]

On Mon, Mar 06, 2023 at 07:23:23PM -0800, Joe Perches wrote:
> On Mon, 2023-03-06 at 22:10 -0500, Joel Fernandes wrote:
> > On Mon, Mar 6, 2023 at 10:08 PM Joe Perches <joe@perches.com> wrote:
> > > 
> > > On Tue, 2023-03-07 at 03:04 +0000, Joel Fernandes (Google) wrote:
> > > > Single-argument kvfree_rcu() usage is being deprecated [1] [2] as it is
> > > > error-prone. However, till all users are converted, we would like to introduce
> > > > checkpatch errors for new patches submitted.
> > > > 
> > > > This patch adds support for the same. Tested with a trial patch.
> > > > 
> > > > For now, we are only considering usages that don't have compound
> > > > nesting, for example ignore: kvfree_rcu( (rcu_head_obj), rcu_head_name).
> > > > This is sufficient as such usages are unlikely.
> > > > 
> > > > Once all users are converted and we remove the old API, we can also revert this
> > > > checkpatch patch then.
> > > 
> > > I think this should be added to the deprecated_apis hash instead
> > > 
> > > our %deprecated_apis = (
> > >         "synchronize_rcu_bh"                    => "synchronize_rcu",
> > >         "synchronize_rcu_bh_expedited"          => "synchronize_rcu_expedited",
> > >         "call_rcu_bh"                           => "call_rcu",
> > >         "rcu_barrier_bh"                        => "rcu_barrier",
> > >         "synchronize_sched"                     => "synchronize_rcu",
> > >         "synchronize_sched_expedited"           => "synchronize_rcu_expedited",
> > >         "call_rcu_sched"                        => "call_rcu",
> > >         "rcu_barrier_sched"                     => "rcu_barrier",
> > >         "get_state_synchronize_sched"           => "get_state_synchronize_rcu",
> > >         "cond_synchronize_sched"                => "cond_synchronize_rcu",
> > >         "kmap"                                  => "kmap_local_page",
> > >         "kunmap"                                => "kunmap_local",
> > >         "kmap_atomic"                           => "kmap_local_page",
> > >         "kunmap_atomic"                         => "kunmap_local",
> > > );
> > 
> > This is not an API name change though, it is a "number of arguments"
> > or argument list change. Is there a different way to do it?
> 
> Ah, no, not really.
> 
> btw: I don't see a single use of this call without a comma in the tree.
> 

Did you look for kvfree_rcu? It is either kvfree_rcu() or kfree_rcu().

thanks,

 - Joel

Re: [PATCH] checkpatch: Error out if deprecated RCU API used

[Joe Perches]

On Tue, 2023-03-07 at 04:41 +0000, Joel Fernandes wrote:
> On Mon, Mar 06, 2023 at 07:23:23PM -0800, Joe Perches wrote:
> > On Mon, 2023-03-06 at 22:10 -0500, Joel Fernandes wrote:
> > > On Mon, Mar 6, 2023 at 10:08 PM Joe Perches <joe@perches.com> wrote:
> > > > 
> > > > On Tue, 2023-03-07 at 03:04 +0000, Joel Fernandes (Google) wrote:
> > > > > Single-argument kvfree_rcu() usage is being deprecated [1] [2] as it is
> > > > > error-prone. However, till all users are converted, we would like to introduce
> > > > > checkpatch errors for new patches submitted.
> > > > > 
> > > > > This patch adds support for the same. Tested with a trial patch.
> > > > > 
> > > > > For now, we are only considering usages that don't have compound
> > > > > nesting, for example ignore: kvfree_rcu( (rcu_head_obj), rcu_head_name).
> > > > > This is sufficient as such usages are unlikely.
> > > > > 
> > > > > Once all users are converted and we remove the old API, we can also revert this
> > > > > checkpatch patch then.
> > > > 
> > > > I think this should be added to the deprecated_apis hash instead
> > > > 
> > > > our %deprecated_apis = (
> > > >         "synchronize_rcu_bh"                    => "synchronize_rcu",
> > > >         "synchronize_rcu_bh_expedited"          => "synchronize_rcu_expedited",
> > > >         "call_rcu_bh"                           => "call_rcu",
> > > >         "rcu_barrier_bh"                        => "rcu_barrier",
> > > >         "synchronize_sched"                     => "synchronize_rcu",
> > > >         "synchronize_sched_expedited"           => "synchronize_rcu_expedited",
> > > >         "call_rcu_sched"                        => "call_rcu",
> > > >         "rcu_barrier_sched"                     => "rcu_barrier",
> > > >         "get_state_synchronize_sched"           => "get_state_synchronize_rcu",
> > > >         "cond_synchronize_sched"                => "cond_synchronize_rcu",
> > > >         "kmap"                                  => "kmap_local_page",
> > > >         "kunmap"                                => "kunmap_local",
> > > >         "kmap_atomic"                           => "kmap_local_page",
> > > >         "kunmap_atomic"                         => "kunmap_local",
> > > > );
> > > 
> > > This is not an API name change though, it is a "number of arguments"
> > > or argument list change. Is there a different way to do it?
> > 
> > Ah, no, not really.
> > 
> > btw: I don't see a single use of this call without a comma in the tree.
> 
> Did you look for kvfree_rcu? It is either kvfree_rcu() or kfree_rcu().

$ git grep -P '\bkv?free_rcu\s*\(' -- '*.[ch]' | grep -v -P 'kv?free_rcu\s*\([^,]+,.*\)'
drivers/infiniband/core/device.c:		kfree_rcu(container_of(dev->port_data, struct ib_port_data_rcu,
drivers/infiniband/core/rdma_core.c:	 * kfree_rcu(). However the object may still have been released and
drivers/target/target_core_configfs.c:			 * callbacks to complete post kfree_rcu(), before allowing
include/linux/rcupdate.h: *     kvfree_rcu(ptr);
include/linux/rcupdate.h:#define kvfree_rcu(...) KVFREE_GET_MACRO(__VA_ARGS__,		\
include/linux/rcutiny.h:	// kvfree_rcu(one_arg) call.
include/rdma/ib_verbs.h:	struct rcu_head		rcu;		/* kfree_rcu() overhead */
include/scsi/scsi_device.h: * @rcu: For kfree_rcu().
kernel/rcu/rcuscale.c:		pr_alert("CONFIG_RCU_LAZY is disabled, falling back to kfree_rcu() for delayed RCU kfree'ing\n");
kernel/rcu/tree.c: * struct kvfree_rcu_bulk_data - single block to store kvfree_rcu() pointers
kernel/rcu/tree.c: * @records: Array of the kvfree_rcu() pointers
kernel/rcu/tree.c: * struct kfree_rcu_cpu_work - single batch of kfree_rcu() requests
kernel/rcu/tree.c: * @head_free: List of kfree_rcu() objects waiting for a grace period
kernel/rcu/tree.c: * @bulk_head_free: Bulk-List of kvfree_rcu() objects waiting for a grace period
kernel/rcu/tree.c: * struct kfree_rcu_cpu - batch up kfree_rcu() requests for RCU grace period
kernel/rcu/tree.c: * @head: List of kfree_rcu() objects not yet waiting for a grace period
kernel/rcu/tree.c: * @bulk_head: Bulk-List of kvfree_rcu() objects not yet waiting for a grace period
kernel/rcu/tree.c: * @krw_arr: Array of batches of kfree_rcu() objects waiting for a grace period
kernel/rcu/tree.c:	 * double-argument of kvfree_rcu().  This happens when the
kernel/rcu/tree.c: * reduce the number of grace periods during heavy kfree_rcu()/kvfree_rcu() load.
kernel/rcu/tree.c:		// Probable double kfree_rcu(), just leak.
net/core/pktgen.c:	/* Don't need rcu_barrier() due to use of kfree_rcu() */

Re: [PATCH] checkpatch: Error out if deprecated RCU API used

[Joel Fernandes]

On Mon, Mar 6, 2023 at 11:53 PM Joe Perches <joe@perches.com> wrote:
>
> On Tue, 2023-03-07 at 04:41 +0000, Joel Fernandes wrote:
> > On Mon, Mar 06, 2023 at 07:23:23PM -0800, Joe Perches wrote:
> > > On Mon, 2023-03-06 at 22:10 -0500, Joel Fernandes wrote:
> > > > On Mon, Mar 6, 2023 at 10:08 PM Joe Perches <joe@perches.com> wrote:
> > > > >
> > > > > On Tue, 2023-03-07 at 03:04 +0000, Joel Fernandes (Google) wrote:
> > > > > > Single-argument kvfree_rcu() usage is being deprecated [1] [2] as it is
> > > > > > error-prone. However, till all users are converted, we would like to introduce
> > > > > > checkpatch errors for new patches submitted.
> > > > > >
> > > > > > This patch adds support for the same. Tested with a trial patch.
> > > > > >
> > > > > > For now, we are only considering usages that don't have compound
> > > > > > nesting, for example ignore: kvfree_rcu( (rcu_head_obj), rcu_head_name).
> > > > > > This is sufficient as such usages are unlikely.
> > > > > >
> > > > > > Once all users are converted and we remove the old API, we can also revert this
> > > > > > checkpatch patch then.
> > > > >
> > > > > I think this should be added to the deprecated_apis hash instead
> > > > >
> > > > > our %deprecated_apis = (
> > > > >         "synchronize_rcu_bh"                    => "synchronize_rcu",
> > > > >         "synchronize_rcu_bh_expedited"          => "synchronize_rcu_expedited",
> > > > >         "call_rcu_bh"                           => "call_rcu",
> > > > >         "rcu_barrier_bh"                        => "rcu_barrier",
> > > > >         "synchronize_sched"                     => "synchronize_rcu",
> > > > >         "synchronize_sched_expedited"           => "synchronize_rcu_expedited",
> > > > >         "call_rcu_sched"                        => "call_rcu",
> > > > >         "rcu_barrier_sched"                     => "rcu_barrier",
> > > > >         "get_state_synchronize_sched"           => "get_state_synchronize_rcu",
> > > > >         "cond_synchronize_sched"                => "cond_synchronize_rcu",
> > > > >         "kmap"                                  => "kmap_local_page",
> > > > >         "kunmap"                                => "kunmap_local",
> > > > >         "kmap_atomic"                           => "kmap_local_page",
> > > > >         "kunmap_atomic"                         => "kunmap_local",
> > > > > );
> > > >
> > > > This is not an API name change though, it is a "number of arguments"
> > > > or argument list change. Is there a different way to do it?
> > >
> > > Ah, no, not really.
> > >
> > > btw: I don't see a single use of this call without a comma in the tree.
> >
> > Did you look for kvfree_rcu? It is either kvfree_rcu() or kfree_rcu().
>
> $ git grep -P '\bkv?free_rcu\s*\(' -- '*.[ch]' | grep -v -P 'kv?free_rcu\s*\([^,]+,.*\)'
> drivers/infiniband/core/device.c:               kfree_rcu(container_of(dev->port_data, struct ib_port_data_rcu,
> drivers/infiniband/core/rdma_core.c:     * kfree_rcu(). However the object may still have been released and
> drivers/target/target_core_configfs.c:                   * callbacks to complete post kfree_rcu(), before allowing
> include/linux/rcupdate.h: *     kvfree_rcu(ptr);
> include/linux/rcupdate.h:#define kvfree_rcu(...) KVFREE_GET_MACRO(__VA_ARGS__,          \
> include/linux/rcutiny.h:        // kvfree_rcu(one_arg) call.
> include/rdma/ib_verbs.h:        struct rcu_head         rcu;            /* kfree_rcu() overhead */
> include/scsi/scsi_device.h: * @rcu: For kfree_rcu().
> kernel/rcu/rcuscale.c:          pr_alert("CONFIG_RCU_LAZY is disabled, falling back to kfree_rcu() for delayed RCU kfree'ing\n");
> kernel/rcu/tree.c: * struct kvfree_rcu_bulk_data - single block to store kvfree_rcu() pointers
> kernel/rcu/tree.c: * @records: Array of the kvfree_rcu() pointers
> kernel/rcu/tree.c: * struct kfree_rcu_cpu_work - single batch of kfree_rcu() requests
> kernel/rcu/tree.c: * @head_free: List of kfree_rcu() objects waiting for a grace period
> kernel/rcu/tree.c: * @bulk_head_free: Bulk-List of kvfree_rcu() objects waiting for a grace period
> kernel/rcu/tree.c: * struct kfree_rcu_cpu - batch up kfree_rcu() requests for RCU grace period
> kernel/rcu/tree.c: * @head: List of kfree_rcu() objects not yet waiting for a grace period
> kernel/rcu/tree.c: * @bulk_head: Bulk-List of kvfree_rcu() objects not yet waiting for a grace period
> kernel/rcu/tree.c: * @krw_arr: Array of batches of kfree_rcu() objects waiting for a grace period
> kernel/rcu/tree.c:       * double-argument of kvfree_rcu().  This happens when the
> kernel/rcu/tree.c: * reduce the number of grace periods during heavy kfree_rcu()/kvfree_rcu() load.
> kernel/rcu/tree.c:              // Probable double kfree_rcu(), just leak.
> net/core/pktgen.c:      /* Don't need rcu_barrier() due to use of kfree_rcu() */
>

Do you mind sharing which tree you are looking at? I checked both
6.3-rc1 and linux-next.

Your grep returned:

kernel/trace/trace_osnoise.c:   kvfree_rcu(inst);
kernel/trace/trace_probe.c:     kvfree_rcu(link);
lib/test_vmalloc.c:             kvfree_rcu(p);
mm/list_lru.c:   * We need kvfree_rcu() here. And the walking of the list
net/core/pktgen.c:      /* Don't need rcu_barrier() due to use of kfree_rcu() */
net/core/sysctl_net_core.c:
kvfree_rcu(orig_sock_table);
net/core/sysctl_net_core.c:                             kfree_rcu(cur);
net/mac802154/scan.c:   kfree_rcu(request);
net/mac802154/scan.c:   kfree_rcu(request);

Re: [PATCH] checkpatch: Error out if deprecated RCU API used

[Joe Perches]

On Tue, 2023-03-07 at 00:11 -0500, Joel Fernandes wrote:

> Do you mind sharing which tree you are looking at? I checked both
> 6.3-rc1 and linux-next.
> 
> Your grep returned:
> 
> kernel/trace/trace_osnoise.c:   kvfree_rcu(inst);
> kernel/trace/trace_probe.c:     kvfree_rcu(link);
> lib/test_vmalloc.c:             kvfree_rcu(p);
> mm/list_lru.c:   * We need kvfree_rcu() here. And the walking of the list
> net/core/pktgen.c:      /* Don't need rcu_barrier() due to use of kfree_rcu() */
> net/core/sysctl_net_core.c:
> kvfree_rcu(orig_sock_table);
> net/core/sysctl_net_core.c:                             kfree_rcu(cur);
> net/mac802154/scan.c:   kfree_rcu(request);
> net/mac802154/scan.c:   kfree_rcu(request);

rather old.  I'm not subscribed and haven't been following much.

Add linux-next specific files for 20230217

Updating to today's next:

Add linux-next specific files for 20230307

I get several instances:

$ git grep -P '\bkv?free_rcu\s*\(' -- '*.[ch]' | grep -v -P 'kv?free_rcu\s*\([^,]+,.*\)'
drivers/block/drbd/drbd_nl.c:	kvfree_rcu(old_disk_conf);
drivers/block/drbd/drbd_nl.c:	kvfree_rcu(old_net_conf);
drivers/block/drbd/drbd_nl.c:		kvfree_rcu(old_disk_conf);
drivers/block/drbd/drbd_receiver.c:	kvfree_rcu(old_net_conf);
drivers/block/drbd/drbd_receiver.c:			kvfree_rcu(old_disk_conf);
drivers/block/drbd/drbd_state.c:		kvfree_rcu(old_conf);
drivers/infiniband/core/device.c:		kfree_rcu(container_of(dev->port_data, struct ib_port_data_rcu,
drivers/infiniband/core/rdma_core.c:	 * kfree_rcu(). However the object may still have been released and
drivers/infiniband/sw/rxe/rxe_mr.c:	kfree_rcu(mr);
drivers/misc/vmw_vmci/vmci_context.c:		kvfree_rcu(notifier);
drivers/misc/vmw_vmci/vmci_event.c:	kvfree_rcu(s);
drivers/net/ethernet/mellanox/mlx5/core/en/tc/int_port.c:	kfree_rcu(int_port);
drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c:	kfree_rcu(tx_sa);
drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c:	kfree_rcu(rx_sc);
drivers/target/target_core_configfs.c:			 * callbacks to complete post kfree_rcu(), before allowing
fs/ext4/super.c:				kfree_rcu(qname);
include/linux/rcupdate.h: *     kvfree_rcu(ptr);
include/linux/rcupdate.h:#define kvfree_rcu(...) KVFREE_GET_MACRO(__VA_ARGS__,		\
include/linux/rcutiny.h:	// kvfree_rcu(one_arg) call.
include/rdma/ib_verbs.h:	struct rcu_head		rcu;		/* kfree_rcu() overhead */
include/scsi/scsi_device.h: * @rcu: For kfree_rcu().
kernel/rcu/rcuscale.c:		pr_alert("CONFIG_RCU_LAZY is disabled, falling back to kfree_rcu() for delayed RCU kfree'ing\n");
kernel/rcu/tree.c: * struct kvfree_rcu_bulk_data - single block to store kvfree_rcu() pointers
kernel/rcu/tree.c: * @records: Array of the kvfree_rcu() pointers
kernel/rcu/tree.c: * struct kfree_rcu_cpu_work - single batch of kfree_rcu() requests
kernel/rcu/tree.c: * @head_free: List of kfree_rcu() objects waiting for a grace period
kernel/rcu/tree.c: * @bulk_head_free: Bulk-List of kvfree_rcu() objects waiting for a grace period
kernel/rcu/tree.c: * struct kfree_rcu_cpu - batch up kfree_rcu() requests for RCU grace period
kernel/rcu/tree.c: * @head: List of kfree_rcu() objects not yet waiting for a grace period
kernel/rcu/tree.c: * @bulk_head: Bulk-List of kvfree_rcu() objects not yet waiting for a grace period
kernel/rcu/tree.c: * @krw_arr: Array of batches of kfree_rcu() objects waiting for a grace period
kernel/rcu/tree.c:	 * double-argument of kvfree_rcu().  This happens when the
kernel/rcu/tree.c: * reduce the number of grace periods during heavy kfree_rcu()/kvfree_rcu() load.
kernel/rcu/tree.c:		// Probable double kfree_rcu(), just leak.
kernel/trace/trace_osnoise.c:	kvfree_rcu(inst);
kernel/trace/trace_probe.c:	kvfree_rcu(link);
net/core/pktgen.c:	/* Don't need rcu_barrier() due to use of kfree_rcu() */
net/core/sysctl_net_core.c:				kvfree_rcu(orig_sock_table);
net/core/sysctl_net_core.c:				kfree_rcu(cur);

Re: [PATCH] checkpatch: Error out if deprecated RCU API used

[Joel Fernandes]

On Tue, Mar 7, 2023 at 12:22 AM Joe Perches <joe@perches.com> wrote:
>
> On Tue, 2023-03-07 at 00:11 -0500, Joel Fernandes wrote:
>
> > Do you mind sharing which tree you are looking at? I checked both
> > 6.3-rc1 and linux-next.
> >
> > Your grep returned:
> >
> > kernel/trace/trace_osnoise.c:   kvfree_rcu(inst);
> > kernel/trace/trace_probe.c:     kvfree_rcu(link);
> > lib/test_vmalloc.c:             kvfree_rcu(p);
> > mm/list_lru.c:   * We need kvfree_rcu() here. And the walking of the list
> > net/core/pktgen.c:      /* Don't need rcu_barrier() due to use of kfree_rcu() */
> > net/core/sysctl_net_core.c:
> > kvfree_rcu(orig_sock_table);
> > net/core/sysctl_net_core.c:                             kfree_rcu(cur);
> > net/mac802154/scan.c:   kfree_rcu(request);
> > net/mac802154/scan.c:   kfree_rcu(request);
>
> rather old.  I'm not subscribed and haven't been following much.
>
> Add linux-next specific files for 20230217

I am surprised though why you don't see the usage in trace_osnoise.c
though because that was added in 2021 (see diff below).

Anyway, I take it you are Ok with the checkpatch patch. If so, do
provide your Ack tag in advance. We can push from our side only if
needed. There is a chance that we may not need it if we are successful
in having made the conversions to the "good API" in time for the next
merge window.

diff --git a/kernel/trace/trace_osnoise.c b/kernel/trace/trace_osnoise.c
index 7520d43aed55..4719a848bf17 100644
--- a/kernel/trace/trace_osnoise.c
+++ b/kernel/trace/trace_osnoise.c
@@ -138,8 +138,7 @@ static void osnoise_unregister_instance(struct
trace_array *tr)
        if (!found)
                return;

-       synchronize_rcu();
-       kfree(inst);
+       kvfree_rcu(inst);
 }

 /*


>
> Updating to today's next:
>
> Add linux-next specific files for 20230307
>
> I get several instances:
>
> $ git grep -P '\bkv?free_rcu\s*\(' -- '*.[ch]' | grep -v -P 'kv?free_rcu\s*\([^,]+,.*\)'
> drivers/block/drbd/drbd_nl.c:   kvfree_rcu(old_disk_conf);
> drivers/block/drbd/drbd_nl.c:   kvfree_rcu(old_net_conf);
> drivers/block/drbd/drbd_nl.c:           kvfree_rcu(old_disk_conf);
> drivers/block/drbd/drbd_receiver.c:     kvfree_rcu(old_net_conf);
> drivers/block/drbd/drbd_receiver.c:                     kvfree_rcu(old_disk_conf);
> drivers/block/drbd/drbd_state.c:                kvfree_rcu(old_conf);
> drivers/infiniband/core/device.c:               kfree_rcu(container_of(dev->port_data, struct ib_port_data_rcu,
> drivers/infiniband/core/rdma_core.c:     * kfree_rcu(). However the object may still have been released and
> drivers/infiniband/sw/rxe/rxe_mr.c:     kfree_rcu(mr);
> drivers/misc/vmw_vmci/vmci_context.c:           kvfree_rcu(notifier);
> drivers/misc/vmw_vmci/vmci_event.c:     kvfree_rcu(s);
> drivers/net/ethernet/mellanox/mlx5/core/en/tc/int_port.c:       kfree_rcu(int_port);
> drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c:      kfree_rcu(tx_sa);
> drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c:      kfree_rcu(rx_sc);
> drivers/target/target_core_configfs.c:                   * callbacks to complete post kfree_rcu(), before allowing
> fs/ext4/super.c:                                kfree_rcu(qname);
> include/linux/rcupdate.h: *     kvfree_rcu(ptr);
> include/linux/rcupdate.h:#define kvfree_rcu(...) KVFREE_GET_MACRO(__VA_ARGS__,          \
> include/linux/rcutiny.h:        // kvfree_rcu(one_arg) call.
> include/rdma/ib_verbs.h:        struct rcu_head         rcu;            /* kfree_rcu() overhead */
> include/scsi/scsi_device.h: * @rcu: For kfree_rcu().
> kernel/rcu/rcuscale.c:          pr_alert("CONFIG_RCU_LAZY is disabled, falling back to kfree_rcu() for delayed RCU kfree'ing\n");
> kernel/rcu/tree.c: * struct kvfree_rcu_bulk_data - single block to store kvfree_rcu() pointers
> kernel/rcu/tree.c: * @records: Array of the kvfree_rcu() pointers
> kernel/rcu/tree.c: * struct kfree_rcu_cpu_work - single batch of kfree_rcu() requests
> kernel/rcu/tree.c: * @head_free: List of kfree_rcu() objects waiting for a grace period
> kernel/rcu/tree.c: * @bulk_head_free: Bulk-List of kvfree_rcu() objects waiting for a grace period
> kernel/rcu/tree.c: * struct kfree_rcu_cpu - batch up kfree_rcu() requests for RCU grace period
> kernel/rcu/tree.c: * @head: List of kfree_rcu() objects not yet waiting for a grace period
> kernel/rcu/tree.c: * @bulk_head: Bulk-List of kvfree_rcu() objects not yet waiting for a grace period
> kernel/rcu/tree.c: * @krw_arr: Array of batches of kfree_rcu() objects waiting for a grace period
> kernel/rcu/tree.c:       * double-argument of kvfree_rcu().  This happens when the
> kernel/rcu/tree.c: * reduce the number of grace periods during heavy kfree_rcu()/kvfree_rcu() load.
> kernel/rcu/tree.c:              // Probable double kfree_rcu(), just leak.
> kernel/trace/trace_osnoise.c:   kvfree_rcu(inst);
> kernel/trace/trace_probe.c:     kvfree_rcu(link);
> net/core/pktgen.c:      /* Don't need rcu_barrier() due to use of kfree_rcu() */
> net/core/sysctl_net_core.c:                             kvfree_rcu(orig_sock_table);
> net/core/sysctl_net_core.c:                             kfree_rcu(cur);
>