On 05/18/2016 02:52 AM, Hannes Reinecke wrote:
Originally libfc would just be initializing the refcount to '1',
and using the disc_mutex to synchronize if and when the final put
should be happening.
This has a race condition as the mutex might be delayed, causing
other threads to access an invalid structure.
This patch updates the rport reference counting to increase the
reference every time 'rport_lookup' is called, and decreases
the reference correspondingly.
This removes the need to hold 'disc_mutex' when removing the
structure, and avoids the above race condition.
Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
---
drivers/scsi/fcoe/fcoe_ctlr.c | 6 ------
drivers/scsi/libfc/fc_lport.c | 19 ++++++++++-------
drivers/scsi/libfc/fc_rport.c | 49 ++++++++++++++++++++++---------------------
3 files changed, 37 insertions(+), 37 deletions(-)
diff --git a/drivers/scsi/fcoe/fcoe_ctlr.c b/drivers/scsi/fcoe/fcoe_ctlr.c
index 3e83d48..59b8476 100644
--- a/drivers/scsi/fcoe/fcoe_ctlr.c
+++ b/drivers/scsi/fcoe/fcoe_ctlr.c
@@ -2496,14 +2496,12 @@ static int fcoe_ctlr_vn_lookup(struct fcoe_ctlr *fip, u32 port_id, u8 *mac)
struct fcoe_rport *frport;
int ret = -1;
- rcu_read_lock();
rdata = lport->tt.rport_lookup(lport, port_id);
if (rdata) {
frport = fcoe_ctlr_rport(rdata);
memcpy(mac, frport->enode_mac, ETH_ALEN);
ret = 0;
}
- rcu_read_unlock();
return ret;
}
Hello Hannes,
Although I'm not very familiar with the SCSI FC code, the approach of
this patch makes sense to me. But it's not clear to me which code drops
the reference that has been obtained by the rport_lookup() call in the
above code?
Bart.
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