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Member "lttng-modules-2.11.0-rc5/lttng-context-prio.c" (11 Jun 2019, 2439 Bytes) of package /linux/misc/lttng-modules-2.11.0-rc5.tar.bz2:


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    1 /* SPDX-License-Identifier: (GPL-2.0 or LGPL-2.1)
    2  *
    3  * lttng-context-prio.c
    4  *
    5  * LTTng priority context.
    6  *
    7  * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
    8  */
    9 
   10 #include <linux/module.h>
   11 #include <linux/slab.h>
   12 #include <linux/sched.h>
   13 #include <lttng-events.h>
   14 #include <wrapper/ringbuffer/frontend_types.h>
   15 #include <wrapper/vmalloc.h>
   16 #include <wrapper/kallsyms.h>
   17 #include <lttng-tracer.h>
   18 
   19 static
   20 int (*wrapper_task_prio_sym)(struct task_struct *t);
   21 
   22 int wrapper_task_prio_init(void)
   23 {
   24     wrapper_task_prio_sym = (void *) kallsyms_lookup_funcptr("task_prio");
   25     if (!wrapper_task_prio_sym) {
   26         printk(KERN_WARNING "LTTng: task_prio symbol lookup failed.\n");
   27         return -EINVAL;
   28     }
   29     return 0;
   30 }
   31 
   32 static
   33 size_t prio_get_size(size_t offset)
   34 {
   35     size_t size = 0;
   36 
   37     size += lib_ring_buffer_align(offset, lttng_alignof(int));
   38     size += sizeof(int);
   39     return size;
   40 }
   41 
   42 static
   43 void prio_record(struct lttng_ctx_field *field,
   44         struct lib_ring_buffer_ctx *ctx,
   45         struct lttng_channel *chan)
   46 {
   47     int prio;
   48 
   49     prio = wrapper_task_prio_sym(current);
   50     lib_ring_buffer_align_ctx(ctx, lttng_alignof(prio));
   51     chan->ops->event_write(ctx, &prio, sizeof(prio));
   52 }
   53 
   54 static
   55 void prio_get_value(struct lttng_ctx_field *field,
   56         struct lttng_probe_ctx *lttng_probe_ctx,
   57         union lttng_ctx_value *value)
   58 {
   59     value->s64 = wrapper_task_prio_sym(current);
   60 }
   61 
   62 int lttng_add_prio_to_ctx(struct lttng_ctx **ctx)
   63 {
   64     struct lttng_ctx_field *field;
   65     int ret;
   66 
   67     if (!wrapper_task_prio_sym) {
   68         ret = wrapper_task_prio_init();
   69         if (ret)
   70             return ret;
   71     }
   72 
   73     field = lttng_append_context(ctx);
   74     if (!field)
   75         return -ENOMEM;
   76     if (lttng_find_context(*ctx, "prio")) {
   77         lttng_remove_context_field(ctx, field);
   78         return -EEXIST;
   79     }
   80     field->event_field.name = "prio";
   81     field->event_field.type.atype = atype_integer;
   82     field->event_field.type.u.basic.integer.size = sizeof(int) * CHAR_BIT;
   83     field->event_field.type.u.basic.integer.alignment = lttng_alignof(int) * CHAR_BIT;
   84     field->event_field.type.u.basic.integer.signedness = lttng_is_signed_type(int);
   85     field->event_field.type.u.basic.integer.reverse_byte_order = 0;
   86     field->event_field.type.u.basic.integer.base = 10;
   87     field->event_field.type.u.basic.integer.encoding = lttng_encode_none;
   88     field->get_size = prio_get_size;
   89     field->record = prio_record;
   90     field->get_value = prio_get_value;
   91     lttng_context_update(*ctx);
   92     wrapper_vmalloc_sync_all();
   93     return 0;
   94 }
   95 EXPORT_SYMBOL_GPL(lttng_add_prio_to_ctx);