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  1. 16 Nov, 2007 2 commits
    • Martin Peschke's avatar
      [SCSI] zfcp: fix cleanup of dismissed error recovery actions · 86e8dfc5
      Martin Peschke authored 
      Calling zfcp_erp_strategy_check_action() after zfcp_erp_action_to_running()
in zfcp_erp_strategy() might cause an unbalanced up() for erp_ready_sem,
which makes the zfcp recovery fail somewhere along the way:

erp thread processing erp_action:
|
|	someone waking up erp thread for erp_action
|	|
|	|		someone else dismissing erp_action:
|	|		|
V	V		V

	write_lock_irqsave(&adapter->erp_lock, flags);
	...
	if (zfcp_erp_action_exists(erp_action) == ZFCP_ERP_ACTION_RUNNING) {
		zfcp_erp_action_to_ready(erp_action);
		up(&adapter->erp_ready_sem);	/* first up() for erp_action */
	}
	write_unlock_irqrestore(&adapter->erp_lock, flags);

write_lock_irqsave(&adapter->erp_lock, flags);
...
zfcp_erp_action_to_running(erp_action);
write_unlock_restore(&adapter->erp_lock, flags);
/* processing erp_action */

			write_lock_irqsave(&adapter->erp_lock, flags);
			...
			erp_action->status |= ZFCP_STATUS_ERP_DISMISSED;
			if (zfcp_erp_action_exists(erp_action) ==
						ZFCP_ERP_ACTION_RUNNING) {
				zfcp_erp_action_to_ready(erp_action);
				up(&adapter->erp_ready_sem);
				/* second, unbalanced up() for erp_action */
			}
			...
			write_unlock_restore(&adapter->erp_lock, flags);

write_lock_irqsave(&adapter->erp_lock, flags);
if (erp_action->status & ZFCP_STATUS_ERP_DISMISSED) {
	zfcp_erp_action_dequeue(erp_action);
	retval = ZFCP_ERP_DISMISSED;
}
...
write_unlock_restore(&adapter->erp_lock, flags);
down(&adapter->erp_ready_sem);
/* this down() is meant to balance the first up() */

The erp thread must not dismiss an erp_action after moving that action to
erp_running_head. Instead it should just go through the down() operation,
which balances the first up(), and run through zfcp_erp_strategy one more
time for the second up(), which eventually cleans up erp_action. Which
is similar to the normal processing of an event for erp_action doing
something asynchronously (e.g. waiting for the completion of an fsf_req).

This only works if we make sure that a dismissed erp_action is passed to
zfcp_erp_strategy() prior to the other action, which caused actions to be
dismissed. Therefore the patch implements this rule: running actions go to
the head of the ready list; new actions go to the tail of the ready list;
the erp thread picks actions to be processed from the ready list's head.
Signed-off-by: default avatarMartin Peschke <mp3@de.ibm.com>
Acked-by: default avatarSwen Schillig <swen@vnet.ibm.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      86e8dfc5
    • Martin Peschke's avatar
      [SCSI] zfcp: fix dismissal of error recovery actions · d0076f77
      Martin Peschke authored 
      zfcp_erp_action_dismiss() used to ignore any actions in the ready list. This
is a bug. Any action superseded by a stronger action needs to be dismissed.
This patch changes zfcp_erp_action_dismiss() so that it dismisses actions
regardless of their list affiliation. The ERP thread is able to handle this.
It is important to kick the erp thread only for actions in the running list,
though, as an imbalance of wakeup signals would confuse the erp thread
otherwise.
Signed-off-by: default avatarMartin Peschke <mp3@de.ibm.com>
Acked-by: default avatarSwen Schillig <swen@vnet.ibm.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      d0076f77
  3. 15 Nov, 2007 1 commit
  5. 14 Nov, 2007 2 commits
    • Tony Battersby's avatar
      [SCSI] iscsi: return data transfer residual for data-out commands · 6ee6a2f0
      Tony Battersby authored 
      Currently, the iSCSI driver returns the data transfer residual for
data-in commands (e.g. read) but not data-out commands (e.g. write).
This patch makes it return the data transfer residual for both types of
commands.
Signed-off-by: default avatarTony Battersby <tonyb@cybernetics.com>
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      6ee6a2f0
    • Tony Battersby's avatar
      [SCSI] iscsi_tcp: fix potential lockup with write commands · 505f76b3
      Tony Battersby authored 
      There is a race condition in iscsi_tcp.c that may cause it to forget
that it received a R2T from the target.  This race may cause a data-out
command (such as a write) to lock up.  The race occurs here:

static int
iscsi_send_unsol_pdu(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
	struct iscsi_tcp_cmd_task *tcp_ctask = ctask->dd_data;
	int rc;

	if (tcp_ctask->xmstate & XMSTATE_UNS_HDR) {
		BUG_ON(!ctask->unsol_count);
		tcp_ctask->xmstate &= ~XMSTATE_UNS_HDR; <---- RACE
		...

static int
iscsi_r2t_rsp(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
{
	...
	tcp_ctask->xmstate |= XMSTATE_SOL_HDR_INIT; <---- RACE
	...

While iscsi_xmitworker() (called from scsi_queue_work()) is preparing to
send unsolicited data, iscsi_tcp_data_recv() (called from
tcp_read_sock()) interrupts it upon receipt of a R2T from the target.
Both contexts do read-modify-write of tcp_ctask->xmstate.  Usually, gcc
on x86 will make &= and |= atomic on UP (not guaranteed of course), but
in this case iscsi_send_unsol_pdu() reads the value of xmstate before
clearing the bit, which causes gcc to read xmstate into a CPU register,
test it, clear the bit, and then store it back to memory.  If the recv
interrupt happens during this sequence, then the XMSTATE_SOL_HDR_INIT
bit set by the recv interrupt will be lost, and the R2T will be
forgotten.

The patch below (against 2.6.24-rc1) converts accesses of xmstate to use
set_bit, clear_bit, and test_bit instead of |= and &=.  I have tested
this patch and verified that it fixes the problem.  Another possible
approach would be to hold a lock during most of the rx/tx setup and
post-processing, and drop the lock only for the actual rx/tx.
Signed-off-by: default avatarTony Battersby <tonyb@cybernetics.com>
Signed-off-by: default avatarMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      505f76b3
  7. 11 Nov, 2007 1 commit
    • Alan Cox's avatar
      [SCSI] aacraid: fix security weakness · 5f78e89b
      Alan Cox authored 
      Actually there are several but one is trivially fixed

1.	FSACTL_GET_NEXT_ADAPTER_FIB ioctl does not lock dev->fib_list
but needs to
2.	Ditto for FSACTL_CLOSE_GET_ADAPTER_FIB
3.	It is possible to construct an attack via the SRB ioctls where
the user obtains assorted elevated privileges. Various approaches are
possible, the trivial ones being things like writing to the raw media
via scsi commands and the swap image of other executing programs with
higher privileges.

So the ioctls should be CAP_SYS_RAWIO - at least all the FIB manipulating
ones. This is a bandaid fix for #3 but probably the ioctls should grow
their own capable checks. The other two bugs need someone competent in that
driver to fix them.
Signed-off-by: default avatarAlan Cox <alan@redhat.com>
Acked-by: default avatarMark Salyzyn <mark_salyzyn@adaptec.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
      5f78e89b
  9. 07 Nov, 2007 3 commits
  11. 06 Nov, 2007 13 commits
  13. 05 Nov, 2007 18 commits
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