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bna: Eliminate Small Race Condition Window in RX Path 

Change details:
 - In a continuous sequence of ifconfig up/down operations, there is a small
   window of race between bnad_set_rx_mode() and bnad_cleanup_rx() while the
   former tries to access rx_info->rx & the latter sets it to NULL. This race
   could lead to bna_rx_mode_set() being called with a NULL (rx_info->rx)
   pointer and a crash.
 - Hold bnad->bna_lock while setting / unsetting rx_info->rx in bnad_setup_rx()
   & bnad_cleanup_rx(), thereby eliminating the race described above.

Signed-off-by: Gurunatha Karaje <gkaraje@brocade.com>
Signed-off-by: Rasesh Mody <rmody@brocade.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Rasesh Mody 2011-09-16 15:06:48 +00:00 committed by David S. Miller
parent 3fb9852f98
commit b9fa1fbf98
1 changed files with 3 additions and 2 deletions
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5
drivers/net/ethernet/brocade/bna/bnad.c
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@ -1875,10 +1875,10 @@ bnad_cleanup_rx(struct bnad *bnad, u32 rx_id)
spin_lock_irqsave(&bnad->bna_lock, flags);
bna_rx_destroy(rx_info->rx);
spin_unlock_irqrestore(&bnad->bna_lock, flags);
rx_info->rx = NULL;
rx_info->rx_id = 0;
spin_unlock_irqrestore(&bnad->bna_lock, flags);
bnad_rx_res_free(bnad, res_info);
}
@ -1932,12 +1932,13 @@ bnad_setup_rx(struct bnad *bnad, u32 rx_id)
spin_lock_irqsave(&bnad->bna_lock, flags);
rx = bna_rx_create(&bnad->bna, bnad, rx_config, &rx_cbfn, res_info,
rx_info);
spin_unlock_irqrestore(&bnad->bna_lock, flags);
if (!rx) {
err = -ENOMEM;
spin_unlock_irqrestore(&bnad->bna_lock, flags);
goto err_return;
}
rx_info->rx = rx;
spin_unlock_irqrestore(&bnad->bna_lock, flags);
/*
* Init NAPI, so that state is set to NAPI_STATE_SCHED,