linux-kernel - Re: [PATCH v2 1/2] libsas: Don't process sas events in static works

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Date:   Wed, 14 Jun 2017 11:18:53 +0200
From:   Johannes Thumshirn <jthumshirn@...e.de>
To:     wangyijing <wangyijing@...wei.com>, jejb@...ux.vnet.ibm.com,
        martin.petersen@...cle.com
Cc:     chenqilin2@...wei.com, hare@...e.com, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org, chenxiang66@...ilicon.com,
        huangdaode@...ilicon.com, wangkefeng.wang@...wei.com,
        zhaohongjiang@...wei.com, dingtianhong@...wei.com,
        guohanjun@...wei.com, yanaijie@...wei.com, hch@....de,
        dan.j.williams@...el.com, emilne@...hat.com, thenzl@...hat.com,
        wefu@...hat.com, charles.chenxin@...wei.com,
        chenweilong@...wei.com, Yousong He <heyousong@...wei.com>
Subject: Re: [PATCH v2 1/2] libsas: Don't process sas events in static works

On 06/14/2017 11:04 AM, wangyijing wrote:
>>>  static void notify_ha_event(struct sas_ha_struct *sas_ha, enum ha_event event)
>>>  {
>>> +	struct sas_ha_event *ev;
>>> +
>>>  	BUG_ON(event >= HA_NUM_EVENTS);
>>>  
>>> -	sas_queue_event(event, &sas_ha->pending,
>>> -			&sas_ha->ha_events[event].work, sas_ha);
>>> +	ev = kzalloc(sizeof(*ev), GFP_ATOMIC);
>>> +	if (!ev)
>>> +		return;
>> GFP_ATOMIC allocations can fail and then no events will be queued *and* we
>> don't report the error back to the caller.
>>
> 
> Yes, it's really a problem, but I don't find a better solution, do you have some suggestion ?

Something like this?

diff --git a/drivers/scsi/hisi_sas/hisi_sas_main.c
b/drivers/scsi/hisi_sas/hisi_sas_main.c
index d622db502ec9..27cd7307d308 100644
--- a/drivers/scsi/hisi_sas/hisi_sas_main.c
+++ b/drivers/scsi/hisi_sas/hisi_sas_main.c
@@ -894,7 +894,11 @@ static int hisi_sas_controller_reset(struct
hisi_hba *hisi_hba)
                hisi_sas_release_tasks(hisi_hba);
                spin_unlock_irqrestore(&hisi_hba->lock, flags);

-               sas_ha->notify_ha_event(sas_ha, HAE_RESET);
+               rc = sas_ha->notify_ha_event(sas_ha, HAE_RESET);
+               if (rc) {
+                       dev_warn(dev, "failed to queue HA event (%d)\n",
rc);
+                       goto out;
+               }
                dev_dbg(dev, "controller reset successful!\n");
        } else
                return -1;
diff --git a/drivers/scsi/libsas/sas_event.c
b/drivers/scsi/libsas/sas_event.c
index aadbd5314c5c..6c91fb31f891 100644
--- a/drivers/scsi/libsas/sas_event.c
+++ b/drivers/scsi/libsas/sas_event.c
@@ -116,7 +116,7 @@ void sas_enable_revalidation(struct sas_ha_struct *ha)
        mutex_unlock(&ha->disco_mutex);
 }

-static void notify_ha_event(struct sas_ha_struct *sas_ha, enum ha_event
event)
+static int notify_ha_event(struct sas_ha_struct *sas_ha, enum ha_event
event)
 {
        BUG_ON(event >= HA_NUM_EVENTS);

diff --git a/include/scsi/libsas.h b/include/scsi/libsas.h
index dd0f72c95abe..5d9cd6d20855 100644
--- a/include/scsi/libsas.h
+++ b/include/scsi/libsas.h
@@ -415,7 +415,7 @@ struct sas_ha_struct {
                                * their siblings when forming wide ports */

        /* LLDD calls these to notify the class of an event. */
-       void (*notify_ha_event)(struct sas_ha_struct *, enum ha_event);
+       int (*notify_ha_event)(struct sas_ha_struct *, enum ha_event);
        void (*notify_port_event)(struct asd_sas_phy *, enum port_event);
        void (*notify_phy_event)(struct asd_sas_phy *, enum phy_event);


-- 
Johannes Thumshirn                                          Storage
jthumshirn@...e.de                                +49 911 74053 689
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