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SubjectRe: [PATCH] Fix SCSI proc oops
   Date: 	Thu, 12 Oct 2000 12:48:27 -0700 (PDT)
From: Linus Torvalds <torvalds@transmeta.com>

David, you know this code, would you mind giving it another pair of
eyes? I hate code that doesn't make sense.

Ok, the deal is that the tpnt->present handling during unregister is
really broken. There is no way for the "if" conditional in question
to differentiate between the following two cases:

1) No host adapters for this tpnt were ever registered
2) All host adapters for this tpns were successfully
removed by this loop above the test in question:

/* Next we go through and remove the instances of the individual hosts
* that were detected */

pcount0 = next_scsi_host;
for (shpnt = scsi_hostlist; shpnt; shpnt = sh1) {

Both events leave us with tpnt->present == 0, but only in the #2 case
do we want to do the unlink and procfs deletions.

It's very easy to fix, Torben can you try this (untested) patch?

--- drivers/scsi/scsi.c.~1~ Wed Oct 4 16:11:38 2000
+++ drivers/scsi/scsi.c Thu Oct 12 18:45:06 2000
@@ -1976,6 +1976,7 @@
struct Scsi_Host *sh1;
struct Scsi_Host *shpnt;
char name[10]; /* host_no>=10^9? I don't think so. */
+ int orig_present;

/*
* First verify that this host adapter is completely free with no pending
@@ -2109,6 +2110,7 @@
* that were detected */

pcount0 = next_scsi_host;
+ orig_present = tpnt->present;
for (shpnt = scsi_hostlist; shpnt; shpnt = sh1) {
sh1 = shpnt->next;
if (shpnt->hostt != tpnt)
@@ -2155,8 +2157,11 @@
(scsi_memory_upper_value - scsi_init_memory_start) / 1024);
#endif

- /* Remove it from the linked list and /proc */
- if (tpnt->present) {
+ /* Remove it from the linked list and /proc, but only if
+ * any hosts were registered to begin with _and_ we were
+ * able to remove all of them above.
+ */
+ if (orig_present && !tpnt->present) {
Scsi_Host_Template **SHTp = &scsi_hosts;
Scsi_Host_Template *SHT;

-
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