linux-kernel - RE: [RESEND PATCH v3 0/2] change UIC command handling

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Message-ID: <001001d9e479$ac74c5d0$055e5170$@samsung.com>
Date:   Mon, 11 Sep 2023 15:32:01 +0900
From:   "Kiwoong Kim" <kwmad.kim@...sung.com>
To:     "'Adrian Hunter'" <adrian.hunter@...el.com>
Cc:     <linux-scsi@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <alim.akhtar@...sung.com>, <avri.altman@....com>,
        <bvanassche@....org>, <jejb@...ux.ibm.com>, <beanhuo@...ron.com>,
        <sc.suh@...sung.com>, <hy50.seo@...sung.com>,
        <sh425.lee@...sung.com>, <kwangwon.min@...sung.com>,
        <junwoo80.lee@...sung.com>, <wkon.kim@...sung.com>,
        "'Martin K. Petersen'" <martin.petersen@...cle.com>
Subject: RE: [RESEND PATCH v3 0/2] change UIC command handling

> >> ufs: poll HCS.UCRDY before issuing a UIC command
> >
> > [ 4671.226480] [3: kworker/u20:29:17140] BUG: scheduling while atomic:
> > kworker/u20:29/17140/0x00000002
> > ..
> > [ 4671.228723] [3: kworker/u20:29:17140]  panic+0x16c/0x388 [
> > 4671.228745] [3: kworker/u20:29:17140]  check_panic_on_warn+0x60/0x94
> > [ 4671.228764] [3: kworker/u20:29:17140]  __schedule_bug+0x6c/0x94 [
> > 4671.228786] [3: kworker/u20:29:17140]  __schedule+0x6f4/0xa64 [
> > 4671.228806] [3: kworker/u20:29:17140]  schedule+0x7c/0xe8 [
> > 4671.228824] [3: kworker/u20:29:17140]
> > schedule_hrtimeout_range_clock+0x98/0x114
> > [ 4671.228841] [3: kworker/u20:29:17140]
> > schedule_hrtimeout_range+0x14/0x24
> > [ 4671.228856] [3: kworker/u20:29:17140]  usleep_range_state+0x60/0x94
> > [ 4671.228871] [3: kworker/u20:29:17140]
> > __ufshcd_send_uic_cmd+0xa0/0x1c4 [ 4671.228893] [3:
> > kworker/u20:29:17140]  ufshcd_uic_pwr_ctrl+0x15c/0x390 [ 4671.228908]
> > [3: kworker/u20:29:17140] ufshcd_uic_hibern8_enter+0x9c/0x25c
> > [ 4671.228922] [3: kworker/u20:29:17140]
> > ufshcd_link_state_transition+0x34/0xb0
> > [ 4671.228939] [3: kworker/u20:29:17140]
> > __ufshcd_wl_suspend+0x3f0/0x4b4
> 
> Do you know what is in that path that makes it an atomic context?

Hi,
This made that.

static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd)
..
        bool reenable_intr = false;

        mutex_lock(&hba->uic_cmd_mutex); <<<<


At first, I was willing to post together w/ the following patch but I've got a suggestion to split the patch set because of different topic and I split the patch set.
- This patch removes the mutex, so it can fix the issue.
https://lore.kernel.org/linux-scsi/1694051306-172962-1-git-send-email-kwmad.kim@samsung.com/


But now I'm thinking again that simply removing the mutex could hurt atomicity of UIC command process
that the original code intended for the first time.
So I think this polling UCRDY should be modified rather than applying removal of the mutex.