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Fix two race conditions.

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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
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=9917
1 changed files with 8 additions and 9 deletions
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17
sys/dev/aic7xxx/aic7xxx.seq
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@ -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