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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Aveline Noir <jm5905938@gmail.com>
Cc: "Bruno Prémont" <bonbons@linux-vserver.org>,
	"Jiri Kosina" <jikos@kernel.org>,
	"Benjamin Tissoires" <bentiss@kernel.org>,
	linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
	syzbot+912222e4cb82423535fa@syzkaller.appspotmail.com,
	linux-rt-devel@lists.linux.dev
Subject: Re: [PATCH 1/2] HID: picolcd: Move output requests out of spinlocked sections
Date: Mon, 28 Sep 2026 14:28:22 +0200	[thread overview]
Message-ID: <20260928122822.JdtAHH3g@linutronix.de> (raw)
In-Reply-To: <CANOyQmGkGwSkwUj-NOKzhQ_mgapoqqoOLaqXaGAjWK8jiknarQ@mail.gmail.com>

On 2026-09-28 13:46:53 [+0200], Aveline Noir wrote:
> Creating a PicoLCD through UHID triggers a sleeping-in-invalid-context
> warning in picolcd_set_contrast() on PREEMPT_RT. hid_hw_request() can

This is not limited to PREEMPT_RT.

> allocate with GFP_KERNEL and wait for a reply through __hid_request(),
> but the driver invokes it while holding data->lock. The same pattern

picolcd_data::lock. The important part is that the lock is a spinlock_t.
Non-PREEMPT_RT builds should complain here, too.

Sebastian

  reply	other threads:[~2026-09-28 12:28 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-28 11:46 [PATCH 0/2] HID: picolcd: Fix output-request and framebuffer locking Aveline Noir
2026-09-28 11:46 ` [PATCH 1/2] HID: picolcd: Move output requests out of spinlocked sections Aveline Noir
2026-09-28 12:28   ` Sebastian Andrzej Siewior [this message]
2026-09-28 12:44     ` Jason Mike
2026-09-28 11:46 ` [PATCH 2/2] HID: picolcd: Avoid framebuffer last-close deadlock Aveline Noir

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