Fix: callstack context alignment calculation

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

diff --git a/lttng-context-callstack.c b/lttng-context-callstack.c
index 4dd984be40fee4e3ef6ba9bbbc2d153244f50ee1..bdc1761ee705669ad8d7c95c8edeede0b434cb34 100644 (file)
--- a/lttng-context-callstack.c
+++ b/lttng-context-callstack.c
@@ -152,17 +152,17 @@ size_t lttng_callstack_get_size(size_t offset, struct lttng_ctx_field *field,
                                struct lib_ring_buffer_ctx *ctx,
                                struct lttng_channel *chan)
 {
-       size_t size = 0;
        struct stack_trace *trace;
        struct field_data *fdata = field->priv;
+       size_t orig_offset = offset;
 
        /* do not write data if no space is available */
        trace = stack_trace_context(field, ctx);
        if (unlikely(!trace)) {
-               size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
-               size += sizeof(unsigned int);
-               size += lib_ring_buffer_align(offset, lttng_alignof(unsigned long));
-               return size;
+               offset += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
+               offset += sizeof(unsigned int);
+               offset += lib_ring_buffer_align(offset, lttng_alignof(unsigned long));
+               return offset - orig_offset;
        }
 
        /* reset stack trace, no need to clear memory */
@@ -179,14 +179,14 @@ size_t lttng_callstack_get_size(size_t offset, struct lttng_ctx_field *field,
                        && trace->entries[trace->nr_entries - 1] == ULONG_MAX) {
                trace->nr_entries--;
        }
-       size += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
-       size += sizeof(unsigned int);
-       size += lib_ring_buffer_align(offset, lttng_alignof(unsigned long));
-       size += sizeof(unsigned long) * trace->nr_entries;
+       offset += lib_ring_buffer_align(offset, lttng_alignof(unsigned int));
+       offset += sizeof(unsigned int);
+       offset += lib_ring_buffer_align(offset, lttng_alignof(unsigned long));
+       offset += sizeof(unsigned long) * trace->nr_entries;
        /* Add our own ULONG_MAX delimiter to show incomplete stack. */
        if (trace->nr_entries == trace->max_entries)
-               size += sizeof(unsigned long);
-       return size;
+               offset += sizeof(unsigned long);
+       return offset - orig_offset;
 }
 
 static