Commits
David Woodhouse committed 1f6ea6e511e
solos-pci: Fix race condition in tasklet RX handling We were seeing faults in the solos-pci receive tasklet when packets arrived for a VCC which was currently being closed: [18842.727906] EIP: [<e082f490>] br2684_push+0x19/0x234 [br2684] SS:ESP 0068:dfb89d14 [18845.090712] [<c13ecff3>] ? do_page_fault+0x0/0x2e1 [18845.120042] [<e082f490>] ? br2684_push+0x19/0x234 [br2684] [18845.153530] [<e084fa13>] solos_bh+0x28b/0x7c8 [solos_pci] [18845.186488] [<e084f711>] ? solos_irq+0x2d/0x51 [solos_pci] [18845.219960] [<c100387b>] ? handle_irq+0x3b/0x48 [18845.247732] [<c10265cb>] ? irq_exit+0x34/0x57 [18845.274437] [<c1025720>] tasklet_action+0x42/0x69 [18845.303247] [<c102643f>] __do_softirq+0x8e/0x129 [18845.331540] [<c10264ff>] do_softirq+0x25/0x2a [18845.358274] [<c102664c>] _local_bh_enable_ip+0x5e/0x6a [18845.389677] [<c102666d>] local_bh_enable+0xb/0xe [18845.417944] [<e08490a8>] ppp_unregister_channel+0x32/0xbb [ppp_generic] [18845.458193] [<e08731ad>] pppox_unbind_sock+0x18/0x1f [pppox] This patch uses an RCU-inspired approach to fix it. In the RX tasklet's find_vcc() function we first refuse to use a VCC which already has the ATM_VF_READY bit cleared. And in the VCC close function, we synchronise with the tasklet to ensure that it can't still be using the VCC before we continue and allow the VCC to be destroyed. Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Tested-by: Nathan Williams <nathan@traverse.com.au> Cc: stable@kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>