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path: root/arch/alpha/kernel/asm-offsets.c
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/*
 * Generate definitions needed by assembly language modules.
 * This code generates raw asm output which is post-processed to extract
 * and format the required data.
 */

#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/kbuild.h>
#include <asm/io.h>

void foo(void)
{
	DEFINE(TI_TASK, offsetof(struct thread_info, task));
	DEFINE(TI_FLAGS, offsetof(struct thread_info, flags));
	DEFINE(TI_CPU, offsetof(struct thread_info, cpu));
	BLANK();

        DEFINE(TASK_BLOCKED, offsetof(struct task_struct, blocked));
        DEFINE(TASK_CRED, offsetof(struct task_struct, cred));
        DEFINE(TASK_REAL_PARENT, offsetof(struct task_struct, real_parent));
        DEFINE(TASK_GROUP_LEADER, offsetof(struct task_struct, group_leader));
        DEFINE(TASK_TGID, offsetof(struct task_struct, tgid));
        BLANK();

        DEFINE(CRED_UID,  offsetof(struct cred, uid));
        DEFINE(CRED_EUID, offsetof(struct cred, euid));
        DEFINE(CRED_GID,  offsetof(struct cred, gid));
        DEFINE(CRED_EGID, offsetof(struct cred, egid));
        BLANK();

	DEFINE(SIZEOF_PT_REGS, sizeof(struct pt_regs));
	DEFINE(PT_PTRACED, PT_PTRACED);
	DEFINE(CLONE_VM, CLONE_VM);
	DEFINE(CLONE_UNTRACED, CLONE_UNTRACED);
	DEFINE(SIGCHLD, SIGCHLD);
	BLANK();

	DEFINE(HAE_CACHE, offsetof(struct alpha_machine_vector, hae_cache));
	DEFINE(HAE_REG, offsetof(struct alpha_machine_vector, hae_register));
}
sition
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 'net/ceph/crypto.c')