perf tools: Restore proper cwd on return from mnt namespace

When reporting on 'record' server we try to retrieve/use the mnt
namespace of the profiled tasks. We use following API with cookie to
hold the return namespace, roughly:

  nsinfo__mountns_enter(struct nsinfo *nsi, struct nscookie *nc)
    setns(newns, 0);
  ...
  new ns related open..
  ...
  nsinfo__mountns_exit(struct nscookie *nc)
    setns(nc->oldns)

Once finished we setns to old namespace, which also sets the current
working directory (cwd) to "/", trashing the cwd we had.

This is mostly fine, because we use absolute paths almost everywhere,
but it screws up 'perf diff':

  # perf diff
  failed to open perf.data: No such file or directory  (try 'perf record' first)
  ...

Adding the current working directory to be part of the cookie and
restoring it in the nsinfo__mountns_exit call.

Signed-off-by: Jiri Olsa <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Krister Johansen <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Fixes: 843ff37bb59e ("perf symbols: Find symbols in different mount namespace")
Link: http://lkml.kernel.org/r/[email protected]
[ No need to check for NULL args for free(), use zfree() for struct members ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

0 files changed, 0 insertions, 0 deletions