1. 02 10月, 2006 1 次提交
  2. 01 7月, 2006 1 次提交
  3. 21 2月, 2006 1 次提交
    • H
      [PATCH] m32r: update sys_tas() routine · cf535ea5
      Hirokazu Takata 提交于
      This patch updates and fixes sys_tas() routine for m32r.
      
      In the previous implementation, a lockup rarely caused at sys_tas()
      routine in SMP environment.
      
      > > The problem is that touching *addr will generate an oops if that page isn't
      > > paged in.  If we convert it to use get_user() then that's an improvement,
      > > but we must not run get_user() under spinlock or local_irq_disable().
      
      I rewrote sys_tas() routine by using "lock -> unlock" instructions, and
      utilizing the m32r's interrupt handling characteristics; the m32r processor
      can accept interrupts only at the 32-bit instruction boundary.  So, the
      "unlock" instruction can be executed continuously after the "lock"
      instruction execution without any interruptions.
      
      In addition, to solve such a page_fault problem, I use a fixup code like
      get_user().
      
      And, as for the kernel lockup problem, we found that a calling
      do_page_fault() routine with disabling interrupts might cause a lockup at
      flush_tlb_others(), because we checked a completion of IPI handler's
      operations in a spin-locked critical section.
      
      Therefore, by using "lock -> unlock" code, we can implement the sys_tas()
      rouitine without disabling interrupts explicitly, then no lockups would
      happen at flush_tlb_others(), I hope.
      
      Compile check and some working test in SMP environment have done.
      Signed-off-by: NHirokazu Takata <takata@linux-m32r.org>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      cf535ea5
  4. 29 11月, 2005 1 次提交
    • H
      [PATCH] m32r: Fix sys_tas() syscall · 91f4ab05
      Hirokazu Takata 提交于
      This patch fixes a deadlock problem of the m32r SMP kernel.
      
      In the m32r kernel, sys_tas() system call is provided as a test-and-set
      function for userspace, for backward compatibility.
      
      In some multi-threading application program, deadlocks were rarely caused
      at sys_tas() funcion.  Such a deadlock was caused due to a collision of
      __pthread_lock() and __pthread_unlock() operations.
      
      The "tas" syscall is repeatedly called by pthread_mutex_lock() to get a
      lock, while a lock variable's value is not 0.  On the other hand,
      pthead_mutex_unlock() sets the lock variable to 0 for unlocking.
      
      In the previous implementation of sys_tas() routine, there was a
      possibility that a unlock operation was ignored in the following case:
      
      - Assume a lock variable (*addr) was equal to 1 before sys_tas() execution.
      - __pthread_unlock() operation is executed by the other processor
        and the lock variable (*addr) is set to 0, between a read operation
        ("oldval = *addr;") and the following write operation ("*addr = 1;")
        during a execution of sys_tas().
      
      In this case, the following write operation ("*addr = 1;") overwrites the
      __pthread_unlock() result, and sys_tas() fails to get a lock in the next
      turn and after that.
      
      According to the attatched patch, sys_tas() returns 0 value in the next
      turn and deadlocks never happen.
      Signed-off-by: NHitoshi Yamamoto <Yamamoto.Hitoshi@ap.MitsubishiElectric.co.jp>
      Signed-off-by: NHirokazu Takata <takata@linux-m32r.org>
      Signed-off-by: NAndrew Morton <akpm@osdl.org>
      Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
      91f4ab05
  5. 17 4月, 2005 1 次提交
    • L
      Linux-2.6.12-rc2 · 1da177e4
      Linus Torvalds 提交于
      Initial git repository build. I'm not bothering with the full history,
      even though we have it. We can create a separate "historical" git
      archive of that later if we want to, and in the meantime it's about
      3.2GB when imported into git - space that would just make the early
      git days unnecessarily complicated, when we don't have a lot of good
      infrastructure for it.
      
      Let it rip!
      1da177e4