scsi: core: pair EH runtime PM get and put

shost->eh_noresume is currently consulted twice in one error handling
iteration: once before scsi_autopm_get_host() and once again before
scsi_autopm_put_host().

That is racy when a PM-triggered error path flips shost->eh_noresume
while the SCSI EH thread is still running.

The problem flow looks like this:
PM path
  ufshcd_set_dev_pwr_mode()
    shost->eh_noresume = 1
    ufshcd_execute_start_stop  <-- trigger EH
    ...
    shost->eh_noresume = 0

EH path
  scsi_error_handler()
    if (!shost->eh_noresume)
      scsi_autopm_get_host()  <-- skipped
    ...
    if (!shost->eh_noresume)
       scsi_autopm_put_host()  <-- executed later

In that case one EH iteration can skip autoresume on entry and still
drop a runtime PM reference on exit. That leaves an unmatched runtime PM
put and can trigger a runtime PM usage count underflow.

Fix this by making eh_noresume a regular bool so it can be accessed with
READ_ONCE() and WRITE_ONCE(). Snapshot it once per EH iteration and use
that snapshot for both runtime PM get and put decisions.

Fixes: ae0751ffc77e ("[SCSI] add flag to skip the runtime PM calls on the host")
Signed-off-by: Hongjie Fang <hongjiefang@asrmicro.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Peter Wang <peter.wang@mediatek.com>
Link: https://patch.msgid.link/20260729111614.2407559-1-hongjiefang@asrmicro.com
Signed-off-by: Martin K. Petersen (Oracle) <mkp@kernel.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/include/scsi/scsi_host.h b/include/scsi/scsi_host.h
index f6b286fa59f2..98b0ccf0813e 100644
--- a/include/scsi/scsi_host.h
+++ b/include/scsi/scsi_host.h
@@ -664,6 +664,9 @@ struct Scsi_Host {
 	/* Asynchronous scan in progress */
 	bool async_scan __guarded_by(&scan_mutex);
 
+	/* Don't resume host in EH */
+	bool eh_noresume;
+
 	unsigned active_mode:2;
 
 	/*
@@ -682,9 +685,6 @@ struct Scsi_Host {
 	/* Task mgmt function in progress */
 	unsigned tmf_in_progress:1;
 
-	/* Don't resume host in EH */
-	unsigned eh_noresume:1;
-
 	/* The controller does not support WRITE SAME */
 	unsigned no_write_same:1;