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484d802d0f
There is no need for complex checking between the last consumed index
and current consumed index, a simple subtraction will do.
This also eliminates the possibility of a permanent transmit queue stall
under the following conditions:
- one CPU bursts ring->size worth of traffic (up to 256 buffers), to the
point where we run out of free descriptors, so we stop the transmit
queue at the end of bcm_sysport_xmit()
- because of our locking, we have the transmit process disable
interrupts which means we can be blocking the TX reclamation process
- when TX reclamation finally runs, we will be computing the difference
between ring->c_index (last consumed index by SW) and what the HW
reports through its register
- this register is masked with (ring->size - 1) = 0xff, which will lead
to stripping the upper bits of the index (register is 16-bits wide)
- we will be computing last_tx_cn as 0, which means there is no work to
be done, and we never wake-up the transmit queue, leaving it
permanently disabled
A practical example is e.g: ring->c_index aka last_c_index = 12, we
pushed 256 entries, HW consumer index = 268, we mask it with 0xff = 12,
so last_tx_cn == 0, nothing happens.
Fixes:
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||
|---|---|---|
| .. | ||
| 3com | ||
| 8390 | ||
| adaptec | ||
| adi | ||
| aeroflex | ||
| agere | ||
| alacritech | ||
| allwinner | ||
| alteon | ||
| altera | ||
| amazon | ||
| amd | ||
| apm | ||
| apple | ||
| aquantia | ||
| arc | ||
| atheros | ||
| aurora | ||
| broadcom | ||
| brocade | ||
| cadence | ||
| calxeda | ||
| cavium | ||
| chelsio | ||
| cirrus | ||
| cisco | ||
| cortina | ||
| davicom | ||
| dec | ||
| dlink | ||
| emulex | ||
| ezchip | ||
| faraday | ||
| freescale | ||
| fujitsu | ||
| hisilicon | ||
| hp | ||
| huawei | ||
| i825xx | ||
| ibm | ||
| intel | ||
| marvell | ||
| mediatek | ||
| mellanox | ||
| micrel | ||
| microchip | ||
| moxa | ||
| myricom | ||
| natsemi | ||
| neterion | ||
| netronome | ||
| nuvoton | ||
| nvidia | ||
| nxp | ||
| oki-semi | ||
| packetengines | ||
| pasemi | ||
| qlogic | ||
| qualcomm | ||
| rdc | ||
| realtek | ||
| renesas | ||
| rocker | ||
| samsung | ||
| seeq | ||
| sfc | ||
| sgi | ||
| silan | ||
| sis | ||
| smsc | ||
| socionext | ||
| stmicro | ||
| sun | ||
| synopsys | ||
| tehuti | ||
| ti | ||
| tile | ||
| toshiba | ||
| tundra | ||
| via | ||
| wiznet | ||
| xilinx | ||
| xircom | ||
| xscale | ||
| dnet.c | ||
| dnet.h | ||
| ec_bhf.c | ||
| ethoc.c | ||
| fealnx.c | ||
| jme.c | ||
| jme.h | ||
| Kconfig | ||
| korina.c | ||
| lantiq_etop.c | ||
| Makefile | ||
| netx-eth.c | ||