1. 09 Oct, 2014 4 commits
    • Steven Rostedt (Red Hat)'s avatar
      ring-buffer: Fix infinite spin in reading buffer · 78a3db11
      Steven Rostedt (Red Hat) authored
      commit 24607f11 upstream.
      
      Commit 651e22f2 "ring-buffer: Always reset iterator to reader page"
      fixed one bug but in the process caused another one. The reset is to
      update the header page, but that fix also changed the way the cached
      reads were updated. The cache reads are used to test if an iterator
      needs to be updated or not.
      
      A ring buffer iterator, when created, disables writes to the ring buffer
      but does not stop other readers or consuming reads from happening.
      Although all readers are synchronized via a lock, they are only
      synchronized when in the ring buffer functions. Those functions may
      be called by any number of readers. The iterator continues down when
      its not interrupted by a consuming reader. If a consuming read
      occurs, the iterator starts from the beginning of the buffer.
      
      The way the iterator sees that a consuming read has happened since
      its last read is by checking the reader "cache". The cache holds the
      last counts of the read and the reader page itself.
      
      Commit 651e22f2 changed what was saved by the cache_read when
      the rb_iter_reset() occurred, making the iterator never match the cache.
      Then if the iterator calls rb_iter_reset(), it will go into an
      infinite loop by checking if the cache doesn't match, doing the reset
      and retrying, just to see that the cache still doesn't match! Which
      should never happen as the reset is suppose to set the cache to the
      current value and there's locks that keep a consuming reader from
      having access to the data.
      
      Fixes: 651e22f2 "ring-buffer: Always reset iterator to reader page"
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      78a3db11
    • Josh Triplett's avatar
      init/Kconfig: Fix HAVE_FUTEX_CMPXCHG to not break up the EXPERT menu · 0000372a
      Josh Triplett authored
      commit 62b4d204 upstream.
      
      commit 03b8c7b6 ("futex: Allow
      architectures to skip futex_atomic_cmpxchg_inatomic() test") added the
      HAVE_FUTEX_CMPXCHG symbol right below FUTEX.  This placed it right in
      the middle of the options for the EXPERT menu.  However,
      HAVE_FUTEX_CMPXCHG does not depend on EXPERT or FUTEX, so Kconfig stops
      placing items in the EXPERT menu, and displays the remaining several
      EXPERT items (starting with EPOLL) directly in the General Setup menu.
      
      Since both users of HAVE_FUTEX_CMPXCHG only select it "if FUTEX", make
      HAVE_FUTEX_CMPXCHG itself depend on FUTEX.  With this change, the
      subsequent items display as part of the EXPERT menu again; the EMBEDDED
      menu now appears as the next top-level item in the General Setup menu,
      which makes General Setup much shorter and more usable.
      Signed-off-by: default avatarJosh Triplett <josh@joshtriplett.org>
      Acked-by: default avatarRandy Dunlap <rdunlap@infradead.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      0000372a
    • Peter Zijlstra's avatar
      perf: fix perf bug in fork() · bee870fc
      Peter Zijlstra authored
      commit 6c72e350 upstream.
      
      Oleg noticed that a cleanup by Sylvain actually uncovered a bug; by
      calling perf_event_free_task() when failing sched_fork() we will not yet
      have done the memset() on ->perf_event_ctxp[] and will therefore try and
      'free' the inherited contexts, which are still in use by the parent
      process.  This is bad..
      Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
      Reported-by: default avatarOleg Nesterov <oleg@redhat.com>
      Reported-by: default avatarSylvain 'ythier' Hitier <sylvain.hitier@gmail.com>
      Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
      Cc: Ingo Molnar <mingo@kernel.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      bee870fc
    • Jan Kara's avatar
      udf: Avoid infinite loop when processing indirect ICBs · 07d209bd
      Jan Kara authored
      commit c03aa9f6 upstream.
      
      We did not implement any bound on number of indirect ICBs we follow when
      loading inode. Thus corrupted medium could cause kernel to go into an
      infinite loop, possibly causing a stack overflow.
      
      Fix the possible stack overflow by removing recursion from
      __udf_read_inode() and limit number of indirect ICBs we follow to avoid
      infinite loops.
      Signed-off-by: default avatarJan Kara <jack@suse.cz>
      Cc: Chuck Ebbert <cebbert.lkml@gmail.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      07d209bd
  2. 05 Oct, 2014 36 commits