LCOV - code coverage report
Current view: top level - lib - ratelimit.c (source / functions) Hit Total Coverage
Test: Real Lines: 16 18 88.9 %
Date: 2020-10-17 15:46:16 Functions: 0 1 0.0 %
Legend: Neither, QEMU, Real, Both Branches: 0 0 -

           Branch data     Line data    Source code
       1                 :            : // SPDX-License-Identifier: GPL-2.0-only
       2                 :            : /*
       3                 :            :  * ratelimit.c - Do something with rate limit.
       4                 :            :  *
       5                 :            :  * Isolated from kernel/printk.c by Dave Young <hidave.darkstar@gmail.com>
       6                 :            :  *
       7                 :            :  * 2008-05-01 rewrite the function and use a ratelimit_state data struct as
       8                 :            :  * parameter. Now every user can use their own standalone ratelimit_state.
       9                 :            :  */
      10                 :            : 
      11                 :            : #include <linux/ratelimit.h>
      12                 :            : #include <linux/jiffies.h>
      13                 :            : #include <linux/export.h>
      14                 :            : 
      15                 :            : /*
      16                 :            :  * __ratelimit - rate limiting
      17                 :            :  * @rs: ratelimit_state data
      18                 :            :  * @func: name of calling function
      19                 :            :  *
      20                 :            :  * This enforces a rate limit: not more than @rs->burst callbacks
      21                 :            :  * in every @rs->interval
      22                 :            :  *
      23                 :            :  * RETURNS:
      24                 :            :  * 0 means callbacks will be suppressed.
      25                 :            :  * 1 means go ahead and do it.
      26                 :            :  */
      27                 :          3 : int ___ratelimit(struct ratelimit_state *rs, const char *func)
      28                 :            : {
      29                 :            :         unsigned long flags;
      30                 :            :         int ret;
      31                 :            : 
      32                 :          3 :         if (!rs->interval)
      33                 :            :                 return 1;
      34                 :            : 
      35                 :            :         /*
      36                 :            :          * If we contend on this state's lock then almost
      37                 :            :          * by definition we are too busy to print a message,
      38                 :            :          * in addition to the one that will be printed by
      39                 :            :          * the entity that is holding the lock already:
      40                 :            :          */
      41                 :          3 :         if (!raw_spin_trylock_irqsave(&rs->lock, flags))
      42                 :            :                 return 0;
      43                 :            : 
      44                 :          3 :         if (!rs->begin)
      45                 :          3 :                 rs->begin = jiffies;
      46                 :            : 
      47                 :          3 :         if (time_is_before_jiffies(rs->begin + rs->interval)) {
      48                 :          1 :                 if (rs->missed) {
      49                 :          1 :                         if (!(rs->flags & RATELIMIT_MSG_ON_RELEASE)) {
      50                 :          0 :                                 printk_deferred(KERN_WARNING
      51                 :            :                                                 "%s: %d callbacks suppressed\n",
      52                 :            :                                                 func, rs->missed);
      53                 :          0 :                                 rs->missed = 0;
      54                 :            :                         }
      55                 :            :                 }
      56                 :          1 :                 rs->begin   = jiffies;
      57                 :          1 :                 rs->printed = 0;
      58                 :            :         }
      59                 :          3 :         if (rs->burst && rs->burst > rs->printed) {
      60                 :          3 :                 rs->printed++;
      61                 :          3 :                 ret = 1;
      62                 :            :         } else {
      63                 :          3 :                 rs->missed++;
      64                 :            :                 ret = 0;
      65                 :            :         }
      66                 :          3 :         raw_spin_unlock_irqrestore(&rs->lock, flags);
      67                 :            : 
      68                 :          3 :         return ret;
      69                 :            : }
      70                 :            : EXPORT_SYMBOL(___ratelimit);
    

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