]> pilppa.com Git - linux-2.6-omap-h63xx.git/commit
[SPARC64]: Fix atomicity of TIF update in flush_thread()
authorMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Sat, 10 Mar 2007 08:19:49 +0000 (00:19 -0800)
committerDavid S. Miller <davem@davemloft.net>
Sat, 10 Mar 2007 08:19:49 +0000 (00:19 -0800)
commitc0a79b229ac0e3a96fc00d5be65a498ceb06ef63
tree5eda8f742f1480abf16952d6ba820be6a95d29b4
parent63abdcdc021063bf1cfcddfd3c1a14a761539807
[SPARC64]: Fix atomicity of TIF update in flush_thread()

Fix atomicity of TIF update in flush_thread() for sparc64

Fixes correctly the race by using *_ti_thread_flag.

Race :

parent process executing :
sys_ptrace()
 (lock_kernel())
 (ptrace_get_task_struct(pid))
 arch_ptrace()
   ptrace_detach()
     ptrace_disable(child);
       clear_singlestep(child);
         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
         (which clears the TIF_SINGLESTEP flag atomically from a different
          process)
 (put_task_struct(child))
 (unlock_kernel())

And at the same time, in the child process :
sys_execve()
 do_execve()
   search_binary_handler()
     load_elf_binary()
       flush_old_exec()
         flush_thread()
           doing a non-atomic thread flag update

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
arch/sparc64/kernel/process.c