linux-kernel - Re: [PATCH v2 1/3] scsi: ufs: Put SCSI host after remove it

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Message-ID: <0101016ef4a3e824-6386cb10-c53c-4f2e-bc07-82f4f4986020-000000@us-west-2.amazonses.com>
Date:   Wed, 11 Dec 2019 11:06:52 +0000
From:   cang@...eaurora.org
To:     Avri Altman <Avri.Altman@....com>
Cc:     asutoshd@...eaurora.org, nguyenb@...eaurora.org,
        rnayak@...eaurora.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com, saravanak@...gle.com, salyzyn@...gle.com,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Pedro Sousa <pedrom.sousa@...opsys.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stanley Chu <stanley.chu@...iatek.com>,
        Bean Huo <beanhuo@...ron.com>,
        Venkat Gopalakrishnan <venkatg@...eaurora.org>,
        Tomas Winkler <tomas.winkler@...el.com>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] scsi: ufs: Put SCSI host after remove it

On 2019-12-11 18:37, Avri Altman wrote:
>> 
>> In ufshcd_remove(), after SCSI host is removed, put it once so that 
>> its resources
>> can be released.
>> 
>> Signed-off-by: Can Guo <cang@...eaurora.org>
> 
> This is not really part of this patchset, is it?
> 

Hi Avri,

I put this change in the same patchset due to
#1. The main patch has dependency on it
#2. Consider a scenario where platform driver is also compiled as a 
module, say ufs_qcom.ko.
     In this case, we have two modules, ufs-qcom.ko and ufs-bsg.ko. If do 
insmod ufs-qcom.ko
     then rmmod ufs-qcom.ko and do insmod ufs-qcom.ko again, without this 
change, because scsi
     host was not release, the new scsi host will have a different host 
number, meaning
     hba->host->host_no will be 1, but not 0. Now if do insmod ufs-bsg.ko 
now, the ufs-bsg dev
     created in /dev/bsg/ will be ufs-bsg1, but not ufs-bsg0. If keep 
trying these operations,
     the ufs-bsg device's name will be messed up. This change make sure 
after ufs-qcom.ko is removed
     and installed back, its hba->host->host_no stays 0, so that ufs-bsg 
device name stays same.

Thanks,

Can Guo.

>> ---
>>  drivers/scsi/ufs/ufshcd.c | 1 +
>>  1 file changed, 1 insertion(+)
>> 
>> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c 
>> index
>> b5966fa..a86b0fd 100644
>> --- a/drivers/scsi/ufs/ufshcd.c
>> +++ b/drivers/scsi/ufs/ufshcd.c
>> @@ -8251,6 +8251,7 @@ void ufshcd_remove(struct ufs_hba *hba)
>>         ufs_bsg_remove(hba);
>>         ufs_sysfs_remove_nodes(hba->dev);
>>         scsi_remove_host(hba->host);
>> +       scsi_host_put(hba->host);
>>         /* disable interrupts */
>>         ufshcd_disable_intr(hba, hba->intr_mask);
>>         ufshcd_hba_stop(hba, true);
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project