Em Tue, Apr 19, 2016 at 07:32:11PM -0700, Chris Phlipot escreveu: > This fixes a bug caused by an unitialized callchain cursor. The crash > frist appeared in: > 6f736735e30f ("perf evsel: Require that callchains be resolved before > calling fprintf_{sym,callchain}") > > The callchain cursor is a struct that contains pointers, that when > uninitialized will cause unpredictable behavior (usually a crash) > when trying to append to the callchain. > > The existing implementation has the following issues: > 1. The callchain cursor used is not initialized, resulting in > unpredictable behavior when used. > 2. The cursor is declared on the stack. Even if it is properly initalized, > the implmentation will leak memory when the function returns, > since all the references to the callchain_nodes allocated by > callchain_cursor_append will be lost when the cursor goes out of > scope. > 3. Storing the cursor on the stack is inefficient. Even if memory is > properly freed when it goes out of scope, a performance penalty > will be incurred due to reallocation of callchain nodes. > callchain_cursor_append is designed to avoid these reallocations > when an existing cursor is reused. > > This patch fixes the crash by replacing cursor_callchain with a reference > to the global callchain_cursor which also resolves all 3 issues mentioned > above. > > How to reproduce the crash: > $ perf record --call-graph=dwarf stress -t 1 -c 1 > $ perf script > /dev/null > Segfault
My bad, applying the patch, thanks! - Arnaldo