[PATCH] if_ixgb: Fix possible sleep-under-mutex bugs (different from Bug 220033)

[Jia-Ju Bai]

The driver may sleep under a mutex, and the function call paths are:
ixgb_init [acquire the mutex]
  ixgb_init_locked
    ixgb_setup_transmit_structures
      bus_dma_tag_create(BUS_DMA_ALLOCNOW) --> may sleep
ixgb_init [acquire the mutex]
  ixgb_init_locked
    ixgb_setup_receive_structures
      ixgb_allocate_receive_structures
        bus_dma_tag_create(BUS_DMA_ALLOCNOW) --> may sleep

The possible fix of these bugs is to add "BUS_DMA_NOWAIT" in bus_dma_tag_create.

These bugs are found by a static analysis tool written by myself, and it is
checked by my review of the FreeBSD code.

Signed-off-by: Jia-Ju Bai <baijiaju1990 at 163.com>
---
 sys/dev/ixgb/if_ixgb.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sys/dev/ixgb/if_ixgb.c b/sys/dev/ixgb/if_ixgb.c
index 430c13c72d1..4cdfe6d4c28 100644
--- a/sys/dev/ixgb/if_ixgb.c
+++ b/sys/dev/ixgb/if_ixgb.c
@@ -1518,7 +1518,7 @@ ixgb_setup_transmit_structures(struct adapter * adapter)
 			       MCLBYTES * IXGB_MAX_SCATTER,	/* maxsize */
 			       IXGB_MAX_SCATTER,	/* nsegments */
 			       MCLBYTES,	/* maxsegsize */
-			       BUS_DMA_ALLOCNOW,	/* flags */
+			       BUS_DMA_ALLOCNOW | BUS_DMA_NOWAIT,	/* flags */
 #if __FreeBSD_version >= 502000
 			       NULL,	/* lockfunc */
 			       NULL,	/* lockfuncarg */
@@ -1856,7 +1856,7 @@ ixgb_allocate_receive_structures(struct adapter * adapter)
 				   MCLBYTES,	/* maxsize */
 				   1,	/* nsegments */
 				   MCLBYTES,	/* maxsegsize */
-				   BUS_DMA_ALLOCNOW,	/* flags */
+				   BUS_DMA_ALLOCNOW | BUS_DMA_NOWAIT,	/* flags */
 #if __FreeBSD_version >= 502000
 				   NULL,	/* lockfunc */
 				   NULL,	/* lockfuncarg */
-- 
2.13.0