lib/ringbuffer/backend_types.h

   1 /* SPDX-License-Identifier: (GPL-2.0-only OR LGPL-2.1-only)
   2  *
   3  * lib/ringbuffer/backend_types.h
   4  *
   5  * Ring buffer backend (types).
   6  *
   7  * Copyright (C) 2008-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   8  */
   9
  10 #ifndef _LIB_RING_BUFFER_BACKEND_TYPES_H
  11 #define _LIB_RING_BUFFER_BACKEND_TYPES_H
  12
  13 #include <linux/cpumask.h>
  14 #include <linux/types.h>
  15 #include <lttng-kernel-version.h>
  16 #include <lttng-cpuhotplug.h>
  17
  18 struct lib_ring_buffer_backend_page {
  19         void *virt;                     /* page virtual address (cached) */
  20         unsigned long pfn;              /* page frame number */
  21 };
  22
  23 struct lib_ring_buffer_backend_pages {
  24         unsigned long mmap_offset;      /* offset of the subbuffer in mmap */
  25         union v_atomic records_commit;  /* current records committed count */
  26         union v_atomic records_unread;  /* records to read */
  27         unsigned long data_size;        /* Amount of data to read from subbuf */
  28         struct lib_ring_buffer_backend_page p[];
  29 };
  30
  31 struct lib_ring_buffer_backend_subbuffer {
  32         /* Identifier for subbuf backend pages. Exchanged atomically. */
  33         unsigned long id;               /* backend subbuffer identifier */
  34 };
  35
  36 struct lib_ring_buffer_backend_counts {
  37         /*
  38          * Counter specific to the sub-buffer location within the ring buffer.
  39          * The actual sequence number of the packet within the entire ring
  40          * buffer can be derived from the formula nr_subbuffers * seq_cnt +
  41          * subbuf_idx.
  42          */
  43         uint64_t seq_cnt;               /* packet sequence number */
  44 };
  45
  46 /*
  47  * Forward declaration of frontend-specific channel and ring_buffer.
  48  */
  49 struct channel;
  50 struct lib_ring_buffer;
  51
  52 struct lib_ring_buffer_backend {
  53         /* Array of ring_buffer_backend_subbuffer for writer */
  54         struct lib_ring_buffer_backend_subbuffer *buf_wsb;
  55         /* ring_buffer_backend_subbuffer for reader */
  56         struct lib_ring_buffer_backend_subbuffer buf_rsb;
  57         /* Array of lib_ring_buffer_backend_counts for the packet counter */
  58         struct lib_ring_buffer_backend_counts *buf_cnt;
  59         /*
  60          * Pointer array of backend pages, for whole buffer.
  61          * Indexed by ring_buffer_backend_subbuffer identifier (id) index.
  62          */
  63         struct lib_ring_buffer_backend_pages **array;
  64         unsigned int num_pages_per_subbuf;
  65
  66         struct channel *chan;           /* Associated channel */
  67         int cpu;                        /* This buffer's cpu. -1 if global. */
  68         union v_atomic records_read;    /* Number of records read */
  69         unsigned int allocated:1;       /* is buffer allocated ? */
  70 };
  71
  72 struct channel_backend {
  73         unsigned long buf_size;         /* Size of the buffer */
  74         unsigned long subbuf_size;      /* Sub-buffer size */
  75         unsigned int subbuf_size_order; /* Order of sub-buffer size */
  76         unsigned int num_subbuf_order;  /*
  77                                          * Order of number of sub-buffers/buffer
  78                                          * for writer.
  79                                          */
  80         unsigned int buf_size_order;    /* Order of buffer size */
  81         unsigned int extra_reader_sb:1; /* has extra reader subbuffer ? */
  82         struct lib_ring_buffer *buf;    /* Channel per-cpu buffers */
  83
  84         unsigned long num_subbuf;       /* Number of sub-buffers for writer */
  85         u64 start_tsc;                  /* Channel creation TSC value */
  86         void *priv;                     /* Client-specific information */
  87         void *priv_ops;                 /* Client-specific ops pointer */
  88         void (*release_priv_ops)(void *priv_ops);
  89 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
  90         struct lttng_cpuhp_node cpuhp_prepare;  /* CPU hotplug prepare */
  91 #else
  92         struct notifier_block cpu_hp_notifier;   /* CPU hotplug notifier */
  93 #endif
  94         /*
  95          * We need to copy config because the module containing the
  96          * source config can vanish before the last reference to this
  97          * channel's streams is released.
  98          */
  99         struct lib_ring_buffer_config config; /* Ring buffer configuration */
 100         cpumask_var_t cpumask;          /* Allocated per-cpu buffers cpumask */
 101         char name[NAME_MAX];            /* Channel name */
 102 };
 103
 104 #endif /* _LIB_RING_BUFFER_BACKEND_TYPES_H */