1. 17 May, 2010 4 commits
    • Linus Torvalds's avatar
      Merge git://git.kernel.org/pub/scm/linux/kernel/git/joern/logfs · 7d32c0ac
      Linus Torvalds authored
      * git://git.kernel.org/pub/scm/linux/kernel/git/joern/logfs:
        logfs: handle powerfail on NAND flash
        logfs: handle errors from get_mtd_device()
        logfs: remove unused variable
        logfs: fix sync
        logfs: fix compile failure
        logfs: initialize li->li_refcount
        logfs: commit reservations under space pressure
        logfs: survive logfs_buf_recover read errors
        logfs: Close i_ino reuse race
        logfs: fix logfs_seek_hole()
        logfs: Return -EINVAL if filesystem image doesn't match
        LogFS: Fix typo in b6349ac8
        logfs: testing the wrong variable
      7d32c0ac
    • Linus Torvalds's avatar
      Merge branch 'bkl/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing · 3d2c978e
      Linus Torvalds authored
      * 'bkl/core' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/random-tracing:
        ptrace: Cleanup useless header
        ptrace: kill BKL in ptrace syscall
      3d2c978e
    • Anton Blanchard's avatar
      atomic_t: Remove volatile from atomic_t definition · 81880d60
      Anton Blanchard authored
      When looking at a performance problem on PowerPC, I noticed some awful code
      generation:
      
      c00000000051fc98:       3b 60 00 01     li      r27,1
      ...
      c00000000051fca0:       3b 80 00 00     li      r28,0
      ...
      c00000000051fcdc:       93 61 00 70     stw     r27,112(r1)
      c00000000051fce0:       93 81 00 74     stw     r28,116(r1)
      c00000000051fce4:       81 21 00 70     lwz     r9,112(r1)
      c00000000051fce8:       80 01 00 74     lwz     r0,116(r1)
      c00000000051fcec:       7d 29 07 b4     extsw   r9,r9
      c00000000051fcf0:       7c 00 07 b4     extsw   r0,r0
      
      c00000000051fcf4:       7c 20 04 ac     lwsync
      c00000000051fcf8:       7d 60 f8 28     lwarx   r11,0,r31
      c00000000051fcfc:       7c 0b 48 00     cmpw    r11,r9
      c00000000051fd00:       40 c2 00 10     bne-    c00000000051fd10
      c00000000051fd04:       7c 00 f9 2d     stwcx.  r0,0,r31
      c00000000051fd08:       40 c2 ff f0     bne+    c00000000051fcf8
      c00000000051fd0c:       4c 00 01 2c     isync
      
      We create two constants, write them out to the stack, read them straight back
      in and sign extend them. What a mess.
      
      It turns out this bad code is a result of us defining atomic_t as a
      volatile int.
      
      We removed the volatile attribute from the powerpc atomic_t definition years
      ago, but commit ea435467 (atomic_t: unify all
      arch definitions) added it back in.
      
      To dig up an old quote from Linus:
      
      > The fact is, volatile on data structures is a bug. It's a wart in the C
      > language. It shouldn't be used.
      >
      > Volatile accesses in *code* can be ok, and if we have "atomic_read()"
      > expand to a "*(volatile int *)&(x)->value", then I'd be ok with that.
      >
      > But marking data structures volatile just makes the compiler screw up
      > totally, and makes code for initialization sequences etc much worse.
      
      And screw up it does :)
      
      With the volatile removed, we see much more reasonable code generation:
      
      c00000000051f5b8:       3b 60 00 01     li      r27,1
      ...
      c00000000051f5c0:       3b 80 00 00     li      r28,0
      ...
      
      c00000000051fc7c:       7c 20 04 ac     lwsync
      c00000000051fc80:       7c 00 f8 28     lwarx   r0,0,r31
      c00000000051fc84:       7c 00 d8 00     cmpw    r0,r27
      c00000000051fc88:       40 c2 00 10     bne-    c00000000051fc98
      c00000000051fc8c:       7f 80 f9 2d     stwcx.  r28,0,r31
      c00000000051fc90:       40 c2 ff f0     bne+    c00000000051fc80
      c00000000051fc94:       4c 00 01 2c     isync
      
      Six instructions less.
      Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      81880d60
    • Anton Blanchard's avatar
      atomic_t: Cast to volatile when accessing atomic variables · f3d46f9d
      Anton Blanchard authored
      In preparation for removing volatile from the atomic_t definition, this
      patch adds a volatile cast to all the atomic read functions.
      Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      f3d46f9d
  2. 16 May, 2010 6 commits
  3. 15 May, 2010 17 commits
  4. 14 May, 2010 13 commits