lib/ringbuffer/backend_types.h

   1 #ifndef _LIB_RING_BUFFER_BACKEND_TYPES_H
   2 #define _LIB_RING_BUFFER_BACKEND_TYPES_H
   3
   4 /*
   5  * lib/ringbuffer/backend_types.h
   6  *
   7  * Ring buffer backend (types).
   8  *
   9  * Copyright (C) 2008-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  10  *
  11  * This library is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; only
  14  * version 2.1 of the License.
  15  *
  16  * This library is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  24  */
  25
  26 #include <linux/cpumask.h>
  27 #include <linux/types.h>
  28 #include <lttng-kernel-version.h>
  29 #include <lttng-cpuhotplug.h>
  30
  31 struct lib_ring_buffer_backend_page {
  32         void *virt;                     /* page virtual address (cached) */
  33         unsigned long pfn;              /* page frame number */
  34 };
  35
  36 struct lib_ring_buffer_backend_pages {
  37         unsigned long mmap_offset;      /* offset of the subbuffer in mmap */
  38         union v_atomic records_commit;  /* current records committed count */
  39         union v_atomic records_unread;  /* records to read */
  40         unsigned long data_size;        /* Amount of data to read from subbuf */
  41         struct lib_ring_buffer_backend_page p[];
  42 };
  43
  44 struct lib_ring_buffer_backend_subbuffer {
  45         /* Identifier for subbuf backend pages. Exchanged atomically. */
  46         unsigned long id;               /* backend subbuffer identifier */
  47 };
  48
  49 struct lib_ring_buffer_backend_counts {
  50         /*
  51          * Counter specific to the sub-buffer location within the ring buffer.
  52          * The actual sequence number of the packet within the entire ring
  53          * buffer can be derived from the formula nr_subbuffers * seq_cnt +
  54          * subbuf_idx.
  55          */
  56         uint64_t seq_cnt;               /* packet sequence number */
  57 };
  58
  59 /*
  60  * Forward declaration of frontend-specific channel and ring_buffer.
  61  */
  62 struct channel;
  63 struct lib_ring_buffer;
  64
  65 struct lib_ring_buffer_backend {
  66         /* Array of ring_buffer_backend_subbuffer for writer */
  67         struct lib_ring_buffer_backend_subbuffer *buf_wsb;
  68         /* ring_buffer_backend_subbuffer for reader */
  69         struct lib_ring_buffer_backend_subbuffer buf_rsb;
  70         /* Array of lib_ring_buffer_backend_counts for the packet counter */
  71         struct lib_ring_buffer_backend_counts *buf_cnt;
  72         /*
  73          * Pointer array of backend pages, for whole buffer.
  74          * Indexed by ring_buffer_backend_subbuffer identifier (id) index.
  75          */
  76         struct lib_ring_buffer_backend_pages **array;
  77         unsigned int num_pages_per_subbuf;
  78
  79         struct channel *chan;           /* Associated channel */
  80         int cpu;                        /* This buffer's cpu. -1 if global. */
  81         union v_atomic records_read;    /* Number of records read */
  82         unsigned int allocated:1;       /* is buffer allocated ? */
  83 };
  84
  85 struct channel_backend {
  86         unsigned long buf_size;         /* Size of the buffer */
  87         unsigned long subbuf_size;      /* Sub-buffer size */
  88         unsigned int subbuf_size_order; /* Order of sub-buffer size */
  89         unsigned int num_subbuf_order;  /*
  90                                          * Order of number of sub-buffers/buffer
  91                                          * for writer.
  92                                          */
  93         unsigned int buf_size_order;    /* Order of buffer size */
  94         unsigned int extra_reader_sb:1; /* has extra reader subbuffer ? */
  95         struct lib_ring_buffer *buf;    /* Channel per-cpu buffers */
  96
  97         unsigned long num_subbuf;       /* Number of sub-buffers for writer */
  98         u64 start_tsc;                  /* Channel creation TSC value */
  99         void *priv;                     /* Client-specific information */
 100         void *priv_ops;                 /* Client-specific ops pointer */
 101         void (*release_priv_ops)(void *priv_ops);
 102 #if (LINUX_VERSION_CODE >= KERNEL_VERSION(4,10,0))
 103         struct lttng_cpuhp_node cpuhp_prepare;  /* CPU hotplug prepare */
 104 #else
 105         struct notifier_block cpu_hp_notifier;   /* CPU hotplug notifier */
 106 #endif
 107         /*
 108          * We need to copy config because the module containing the
 109          * source config can vanish before the last reference to this
 110          * channel's streams is released.
 111          */
 112         struct lib_ring_buffer_config config; /* Ring buffer configuration */
 113         cpumask_var_t cpumask;          /* Allocated per-cpu buffers cpumask */
 114         char name[NAME_MAX];            /* Channel name */
 115 };
 116
 117 #endif /* _LIB_RING_BUFFER_BACKEND_TYPES_H */