d/freebsd-skq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Fix two race conditions.

Browse Source 
The first could occur because the original code would continue to reset
the SCSIID register while waiting for a selection.  This could potentially
conflict with a reconnect since a successfull reconnect will also set the
SCSIID register.  The fix is to use a separate wait loop after starting
a selection (as was done a few revisions ago).

The second probably never happens, but it was possible for a target to
reconnect while there was a pending SCB on the waiting list and not get
noticed.  The fix was to remove a supurflous check of the scb waiting
list.
This commit is contained in:
Justin T. Gibbs 1995-08-05 06:59:17 +00:00
parent 2ad17ba679
commit 116616a829
1 changed files with 8 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
sys/dev/aic7xxx/aic7xxx.seq
View File

@ -41,7 +41,7 @@
#
##-M#########################################################################
VERSION AIC7XXX_SEQ_VER "$Id: aic7xxx.seq,v 1.17 1995/07/04 20:58:57 gibbs Exp $"
VERSION AIC7XXX_SEQ_VER "$Id: aic7xxx.seq,v 1.18 1995/07/31 08:21:59 gibbs Exp $"
SCBMASK = 0x1f
@ -268,19 +268,15 @@ SCB_LIST_NULL = 0xff
# Poll QINCNT for work - the lower bits contain
# the number of entries in the Queue In FIFO.
#
start:
cmp WAITING_SCBH,SCB_LIST_NULL jne start_waiting
poll_for_work:
test FLAGS,TWIN_BUS jz start2 # Are we a twin channel device?
# For fairness, we check the other bus first, since we just finished a
# transaction on the current channel.
xor SBLKCTL,0x08 # Toggle to the other bus
test SSTAT0,SELDI jnz reselect
test SSTAT0,SELDO jnz select
xor SBLKCTL,0x08 # Toggle to the original bus
start2:
test SSTAT0,SELDI jnz reselect
test SSTAT0,SELDO jnz select
cmp WAITING_SCBH,SCB_LIST_NULL jne start_waiting
test QINCNT,SCBMASK jz poll_for_work
@ -388,7 +384,7 @@ start_selection:
# so we interrupt the driver, allow it to fill the message buffer, and
# then go back into the arbitration loop
mvi INTSTAT,AWAITING_MSG
jmp poll_for_work
jmp wait_for_selection
identify:
mov SCBARRAY+1 call disconnect # disconnect ok?
@ -418,7 +414,10 @@ mk_tag_done:
mov DINDEX call mk_dtr # build DTR message if needed
!message:
jmp poll_for_work
wait_for_selection:
test SSTAT0,SELDI jnz reselect
test SSTAT0,SELDO jnz select
jmp wait_for_selection
# Reselection has been initiated by a target. Make a note that we've been
# reselected, but haven't seen an IDENTIFY message from the target
@ -706,7 +705,7 @@ clear_a:
# complete. This is so that any action that might require carefull timing
# with the completion of this command can occur.
mvi INTSTAT,IMMEDDONE
jmp start
jmp poll_for_work
complete:
mov QOUTFIFO,SCBPTR
mvi INTSTAT,CMDCMPLT
@ -883,7 +882,7 @@ p_busfree:
# if this is an immediate command, perform a psuedo command complete to
# notify the driver.
test SCBARRAY+11,0xff jz status_ok
jmp start
jmp poll_for_work
# Instead of a generic bcopy routine that requires an argument, we unroll
# the two cases that are actually used, and call them explicitly. This