Function report

Linux Kernel

v5.5.9

Brick Technologies Co., Ltd

Source Code:kernel\trace\trace.c Create Date:2022-07-28 12:01:54
Last Modify:2020-03-12 14:18:49 Copyright©Brick
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Annotation kernel can get tool activityDownload SCCTChinese

Name:tracing_entries_read

Proto:static ssize_t tracing_entries_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)

Type:ssize_t

Parameter:

TypeParameterName
struct file *filp
char __user *ubuf
size_tcnt
loff_t *ppos
6342  inode = file_inode(filp)
6343  tr = s or device private pointer
6344  cpu = Should be used after trace_array_get(), trace_types_lock* ensures that i_cdev was already initialized.
6346  r = 0
6349  mutex_lock( & race_types_lock is used to protect the trace_types list.)
6351  If cpu == RING_BUFFER_ALL_CPUS Then
6355  size = 0
6356  buf_size_same = 1
6358  for_each_tracing_cpu(cpu)
6360  If size == 0 Then size = ({
6361  ({
6361  Do
6361  const void * __vpp_verify = NULL
6361  When 0 cycle
6361  data
6361  })
6361  })->entries
6362  if (size != ({
6362  ({
6362  Do
6362  const void * __vpp_verify = NULL
6362  When 0 cycle
6362  data
6362  })
6362  })->entries)
6363  buf_size_same = 0
6364  Break
6368  If buf_size_same Then
6369  If Not On boot up, the ring buffer is set to the minimum size, so that* we do not waste memory on systems that are not using tracing. Then r = sprintf(buf, "%lu (expanded: %lu)\n", size >> 10, trace_buf_size >> 10)
6373  Else r = sprintf(buf, "%lu\n", size >> 10)
6375  Else r = sprintf(buf, "X\n")
6377  Else r = sprintf(buf, "%lu\n", entries >> 10)
6380  mutex_unlock - release the mutex*@lock: the mutex to be released* Unlock a mutex that has been locked by this task previously.* This function must not be used in interrupt context. Unlocking* of a not locked mutex is not allowed.
6382  ret = simple_read_from_buffer(ubuf, cnt, ppos, buf, r)
6383  Return ret