iwlegacy: fix enqueue hcmd race conditions
authorStanislaw Gruszka <sgruszka@redhat.com>
Thu, 28 Apr 2011 09:51:31 +0000 (11:51 +0200)
committerJohn W. Linville <linville@tuxdriver.com>
Fri, 29 Apr 2011 19:36:14 +0000 (15:36 -0400)
commit81e63263aa3c5bfa64aa3206f4be3e59afc1c183
tree6574c26f54772f16231aac2b329134c63a1a7376
parent93fd74e3d5471c4c91a239599a88fa7e52686e71
iwlegacy: fix enqueue hcmd race conditions

We mark command as huge by using meta->flags from other (non huge) command,
but flags can be possibly overridden, when non huge command is enqueued,
what can lead to:

WARNING: at lib/dma-debug.c:696 dma_debug_device_change+0x1a3/0x1f0()
DMA-API: device driver has pending DMA allocations while released from device [count=1]

To fix introduce additional CMD_MAPPED to mark command as mapped and
serialize iwl_enqueue_hcmd() with iwl_tx_cmd_complete() using
hcmd_lock. Serialization will also fix possible race conditions,
because q->read_ptr, q->write_ptr are modified/used in parallel.

Do not change callback, I did (and fixed) that mistake in iwlagn.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
drivers/net/wireless/iwlegacy/iwl-dev.h
drivers/net/wireless/iwlegacy/iwl-tx.c