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path: root/include/net/tc_act/tc_sample.h
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#ifndef __NET_TC_SAMPLE_H
#define __NET_TC_SAMPLE_H

#include <net/act_api.h>
#include <linux/tc_act/tc_sample.h>
#include <net/psample.h>

struct tcf_sample {
	struct tc_action common;
	u32 rate;
	bool truncate;
	u32 trunc_size;
	struct psample_group __rcu *psample_group;
	u32 psample_group_num;
	struct list_head tcfm_list;
	struct rcu_head rcu;
};
#define to_sample(a) ((struct tcf_sample *)a)

static inline bool is_tcf_sample(const struct tc_action *a)
{
#ifdef CONFIG_NET_CLS_ACT
	return a->ops && a->ops->type == TCA_ACT_SAMPLE;
#else
	return false;
#endif
}

static inline __u32 tcf_sample_rate(const struct tc_action *a)
{
	return to_sample(a)->rate;
}

static inline bool tcf_sample_truncate(const struct tc_action *a)
{
	return to_sample(a)->truncate;
}

static inline int tcf_sample_trunc_size(const struct tc_action *a)
{
	return to_sample(a)->trunc_size;
}

static inline struct psample_group *
tcf_sample_psample_group(const struct tc_action *a)
{
	return rcu_dereference(to_sample(a)->psample_group);
}

#endif /* __NET_TC_SAMPLE_H */
o the reference may actually be acquired but the routines return "false" which results in a reference leak since the caller assumes it does not need to do a corresponding percpu_ref_put(). This was seen when performing CPU hotplug during I/O, as hangs in blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start) raced with percpu_ref_tryget (blk_mq_timeout_work). Sample stack trace: __switch_to+0x2c0/0x450 __schedule+0x2f8/0x970 schedule+0x48/0xc0 blk_mq_freeze_queue_wait+0x94/0x120 blk_mq_queue_reinit_work+0xb8/0x180 blk_mq_queue_reinit_prepare+0x84/0xa0 cpuhp_invoke_callback+0x17c/0x600 cpuhp_up_callbacks+0x58/0x150 _cpu_up+0xf0/0x1c0 do_cpu_up+0x120/0x150 cpu_subsys_online+0x64/0xe0 device_online+0xb4/0x120 online_store+0xb4/0xc0 dev_attr_store+0x68/0xa0 sysfs_kf_write+0x80/0xb0 kernfs_fop_write+0x17c/0x250 __vfs_write+0x6c/0x1e0 vfs_write+0xd0/0x270 SyS_write+0x6c/0x110 system_call+0x38/0xe0 Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS, and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests. However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0 and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set. The fix is to make the tryget routines use an actual boolean internally instead of the atomic long result truncated to a int. Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751 Signed-off-by: Douglas Miller <dougmill@linux.vnet.ibm.com> Reviewed-by: Jens Axboe <axboe@fb.com> Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints") Cc: stable@vger.kernel.org # v3.18+
Diffstat (limited to 'include/xen/interface/elfnote.h')