qlge allocates chunks from a page that it maps and unmaps that page when
the last chunk is released. When the driver is unloaded or the card is
removed, all chunks are released and the page is unmapped for the last
chunk.

However, when the last chunk of a page is not allocated and the device
is removed, that page is not unmapped. In fact, its last reference is
not put and there's also a page leak. This bug prevents a device from
being properly hotplugged.

When the DMA API debug option is enabled, the following messages show
the pending DMA allocation after we remove the driver.

This patch fixes the bug by unmapping and putting the page from the ring
if its last chunk has not been allocated.

pci 0005:98:00.0: DMA-API: device driver has pending DMA allocations while released from device [count=1]
One of leaked entries details: [device address=0x0000000060a80000] [size=65536 bytes] [mapped with DMA_FROM_DEVICE] [mapped as page]
------------[ cut here ]------------
WARNING: at lib/dma-debug.c:746
Modules linked in: qlge(-) rpadlpar_io rpaphp pci_hotplug fuse [last unloaded: qlge]
NIP: c0000000003fc3ec LR: c0000000003fc3e8 CTR: c00000000054de60
REGS: c0000003ee9c74e0 TRAP: 0700   Tainted: G           O  (3.7.2)
MSR: 8000000000029032 <SF,EE,ME,IR,DR,RI>  CR: 28002424  XER: 00000001
SOFTE: 1
CFAR: c0000000007a39c8
TASK = c0000003ee8d5c90[8406] 'rmmod' THREAD: c0000003ee9c4000 CPU: 31
GPR00: c0000000003fc3e8 c0000003ee9c7760 c000000000c789f8 00000000000000ee
GPR04: 0000000000000000 00000000000000ef 0000000000004000 0000000000010000
GPR08: 00000000000000be c000000000b22088 c000000000c4c218 00000000007c0000
GPR12: 0000000028002422 c00000000ff26c80 0000000000000000 000001001b0f1b40
GPR16: 00000000100cb9d8 0000000010093088 c000000000cdf910 0000000000000001
GPR20: 0000000000000000 c000000000dbfc00 0000000000000000 c000000000dbfb80
GPR24: c0000003fafc9d80 0000000000000001 000000000001ff80 c0000003f38f7888
GPR28: c000000000ddfc00 0000000000000400 c000000000bd7790 c000000000ddfb80
NIP [c0000000003fc3ec] .dma_debug_device_change+0x22c/0x2b0
LR [c0000000003fc3e8] .dma_debug_device_change+0x228/0x2b0
Call Trace:
[c0000003ee9c7760] [c0000000003fc3e8] .dma_debug_device_change+0x228/0x2b0 (unreliable)
[c0000003ee9c7840] [c00000000079a098] .notifier_call_chain+0x78/0xf0
[c0000003ee9c78e0] [c0000000000acc20] .__blocking_notifier_call_chain+0x70/0xb0
[c0000003ee9c7990] [c0000000004a9580] .__device_release_driver+0x100/0x140
[c0000003ee9c7a20] [c0000000004a9708] .driver_detach+0x148/0x150
[c0000003ee9c7ac0] [c0000000004a8144] .bus_remove_driver+0xc4/0x150
[c0000003ee9c7b60] [c0000000004aa58c] .driver_unregister+0x8c/0xe0
[c0000003ee9c7bf0] [c0000000004090b4] .pci_unregister_driver+0x34/0xf0
[c0000003ee9c7ca0] [d000000002231194] .qlge_exit+0x1c/0x34 [qlge]
[c0000003ee9c7d20] [c0000000000e36d8] .SyS_delete_module+0x1e8/0x290
[c0000003ee9c7e30] [c0000000000098d4] syscall_exit+0x0/0x94
Instruction dump:
7f26cb78 e818003a e87e81a0 e8f80028 e9180030 796b1f24 78001f24 7d6a5a14
7d2a002a e94b0020 483a7595 60000000 <0fe00000> 2fb80000 40de0048 80120050
---[ end trace 4294f9abdb01031d ]---
Mapped at:
 [<d000000002222f54>] .ql_update_lbq+0x384/0x580 [qlge]
 [<d000000002227bd0>] .ql_clean_inbound_rx_ring+0x300/0xc60 [qlge]
 [<d0000000022288cc>] .ql_napi_poll_msix+0x39c/0x5a0 [qlge]
 [<c0000000006b3c50>] .net_rx_action+0x170/0x300
 [<c000000000081840>] .__do_softirq+0x170/0x300
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@linux.vnet.ibm.com>
Acked-by: Jitendra Kalsaria <Jitendra.kalsaria@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>