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  1. 16 4月, 2016 3 次提交
    • H
      s390: add CPU_BIG_ENDIAN config option · 2fd92273
      由 Heiko Carstens 提交于 
      Make sure that s390 appears to be a big endian machine by defining
this config option.

Without this s390 appears to be little endian as seen by e.g. the
recordmount script: "perl ./scripts/recordmcount.pl "s390" "little"
"64""
This has no practical impact within the script since the endian
variable is only evaluated for mips. However there are already a
couple of common code places which evaluate this config option. None
of them is relevant for s390 currently though.

To avoid any issues in the future (and fix the recordmcount oddity)
add the new config option.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
      2fd92273
    • H
      s390/spinlock: avoid yield to non existent cpu · 84976952
      由 Heiko Carstens 提交于 
      arch_spin_lock_wait_flags() checks if a spinlock is not held before
trying a compare and swap instruction. If the lock is unlocked it
tries the compare and swap instruction, however if a different cpu
grabbed the lock in the meantime the instruction will fail as
expected.

Subsequently the arch_spin_lock_wait_flags() incorrectly tries to
figure out if the cpu that holds the lock is running. However it is
using the wrong cpu number for this (-1) and then will also yield the
current cpu to the wrong cpu.

Fix this by adding a missing continue statement.

Fixes: 470ada6b ("s390/spinlock: refactor arch_spin_lock_wait[_flags]")
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
      84976952
    • G
      s390/dcssblk: fix possible deadlock in remove vs. per-device attributes · 1378a683
      由 Gerald Schaefer 提交于 
      dcssblk_remove_store() holds the dcssblk_devices_sem semaphore while
calling device_unregister(), which in turn tries to acquire the kernfs
kn->dev_map rwsem for the device sysfs subtree. The same rwsem is also
acquired when using the per-device sysfs attributes in the device sub-tree,
and the attribute handlers then also acquire the dcssblk_devices_sem.

This can lead to a deadlock when removing a DCSS while concurrently
reading from / writing to one of its sysfs attributes. The following
lockdep warning hinted towards the issue (CPU0 = dcssblk_remove_store,
CPU1 = dcssblk_shared_store):

[   76.496047]  Possible unsafe locking scenario:

[   76.496054]        CPU0                    CPU1
[   76.496059]        ----                    ----
[   76.496087]   lock(&dcssblk_devices_sem);
[   76.496090]                                lock(s_active#175);
[   76.496106]                                lock(&dcssblk_devices_sem);
[   76.496110]   lock(s_active#175);
[   76.496115]
 *** DEADLOCK ***

Fix this by releasing the dcssblk_devices_sem semaphore, which only
protects internal DCSS data, before calling device_unregister().
Signed-off-by: NGerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
      1378a683
  3. 01 4月, 2016 13 次提交
  5. 31 3月, 2016 12 次提交
  7. 30 3月, 2016 2 次提交
  9. 29 3月, 2016 9 次提交
  11. 28 3月, 2016 1 次提交