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rt: Fix the 0 bytes lost issue

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This is a workaround for #1815. libev uses realloc(0) to
free the loop, which valgrind doesn't like. We have suppressions
to make valgrind ignore them.

Valgrind also has a sanity check when collecting allocation backtraces
that the stack pointer must be at least 512 bytes into the stack (at
least 512 bytes of frames must have come before). When this is not
the case it doesn't collect the backtrace.

Unfortunately, with our spaghetti stacks that valgrind check triggers
sometimes and we don't get the backtrace for the realloc(0), it
fails to be suppressed, and it gets reported as 0 bytes lost
from a malloc with no backtrace.

This fixes the issue by alloca'ing 512 bytes before calling uv_loop_delete
This commit is contained in:
Brian Anderson 2012-04-03 17:06:45 -07:00
parent 1f892dcb01
commit f4b293f0e3
2 changed files with 17 additions and 9 deletions
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10
src/etc/x86.supp
View File

@ -374,15 +374,7 @@
}
{
libuv-0-byte-realloc1
Memcheck:Leak
fun:malloc
...
fun:uv_loop_delete
}
{
libuv-0-byte-realloc2
libuv-0-byte-realloc
Memcheck:Leak
fun:malloc
...

16
src/rt/rust_uv.cpp
View File

@ -83,6 +83,22 @@ rust_uv_loop_new() {
extern "C" void
rust_uv_loop_delete(uv_loop_t* loop) {
// FIXME: This is a workaround for #1815. libev uses realloc(0) to
// free the loop, which valgrind doesn't like. We have suppressions
// to make valgrind ignore them.
//
// Valgrind also has a sanity check when collecting allocation backtraces
// that the stack pointer must be at least 512 bytes into the stack (at
// least 512 bytes of frames must have come before). When this is not
// the case it doesn't collect the backtrace.
//
// Unfortunately, with our spaghetti stacks that valgrind check triggers
// sometimes and we don't get the backtrace for the realloc(0), it
// fails to be suppressed, and it gets reported as 0 bytes lost
// from a malloc with no backtrace.
//
// This pads our stack with some extra space before deleting the loop
alloca(512);
uv_loop_delete(loop);
}