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author | gibbs <gibbs@FreeBSD.org> | 1995-08-05 06:59:17 +0000 |
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committer | gibbs <gibbs@FreeBSD.org> | 1995-08-05 06:59:17 +0000 |
commit | 1df678461b6db6efcb1cef97367cc24bb226406b (patch) | |
tree | 0b3bad3d5365bd2b280988bdb88a8d64f44557b8 | |
parent | 5e2d56d556d82e5810424fb54b41cdc56395c970 (diff) | |
download | FreeBSD-src-1df678461b6db6efcb1cef97367cc24bb226406b.zip FreeBSD-src-1df678461b6db6efcb1cef97367cc24bb226406b.tar.gz |
Fix two race conditions.
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.
-rw-r--r-- | sys/dev/aic7xxx/aic7xxx.seq | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/sys/dev/aic7xxx/aic7xxx.seq b/sys/dev/aic7xxx/aic7xxx.seq index 053ba48..38c2663 100644 --- a/sys/dev/aic7xxx/aic7xxx.seq +++ b/sys/dev/aic7xxx/aic7xxx.seq @@ -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 |