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path: root/sound/firewire/iso-resources.h
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#ifndef SOUND_FIREWIRE_ISO_RESOURCES_H_INCLUDED
#define SOUND_FIREWIRE_ISO_RESOURCES_H_INCLUDED

#include <linux/mutex.h>
#include <linux/types.h>

struct fw_unit;

/**
 * struct fw_iso_resources - manages channel/bandwidth allocation
 * @channels_mask: if the device does not support all channel numbers, set this
 *                 bit mask to something else than the default (all ones)
 *
 * This structure manages (de)allocation of isochronous resources (channel and
 * bandwidth) for one isochronous stream.
 */
struct fw_iso_resources {
	u64 channels_mask;
	/* private: */
	struct fw_unit *unit;
	struct mutex mutex;
	unsigned int channel;
	unsigned int bandwidth; /* in bandwidth units, without overhead */
	unsigned int bandwidth_overhead;
	int generation; /* in which allocation is valid */
	bool allocated;
};

int fw_iso_resources_init(struct fw_iso_resources *r,
			  struct fw_unit *unit);
void fw_iso_resources_destroy(struct fw_iso_resources *r);

int fw_iso_resources_allocate(struct fw_iso_resources *r,
			      unsigned int max_payload_bytes, int speed);
int fw_iso_resources_update(struct fw_iso_resources *r);
void fw_iso_resources_free(struct fw_iso_resources *r);

#endif
eak during percpu-atomic transition
percpu_ref_tryget() and percpu_ref_tryget_live() should return "true" IFF they acquire a reference. But the return value from atomic_long_inc_not_zero() is a long and may have high bits set, e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines is bool so 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 'tools/perf/arch/arm/util/dwarf-regs.c')