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Sun, 17 Aug 2025 07:27:14 -0700 (PDT) Date: Sun, 17 Aug 2025 10:27:11 -0400 From: Alan Stern To: Yunseong Kim Cc: linux-usb@vger.kernel.org, gregkh@linuxfoundation.org, Andrey Konovalov , Shuah Khan , Thomas Gleixner , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt , linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller@googlegroups.com Subject: Re: [BUG] usbip: vhci: Sleeping function called from invalid context in vhci_urb_enqueue on PREEMPT_RT Message-ID: <2bf33071-e05e-4b89-b149-30b90888606f@rowland.harvard.edu> References: <28544110-3021-43da-b32e-9785c81a42c1@kzalloc.com> <1088432b-b433-4bab-a927-69e55d9eb433@rowland.harvard.edu> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1088432b-b433-4bab-a927-69e55d9eb433@rowland.harvard.edu> On Sat, Aug 16, 2025 at 10:16:34AM -0400, Alan Stern wrote: > So it looks like we should be using a different function instead of > local_irq_disable(). We need something which in a non-RT build will > disable interrupts on the local CPU, but in an RT build will merely > disable preemption. (In fact, every occurrence of local_irq_disable() > in the USB subsystem probably should be changed in this way.) Or maybe what we need is something that in a non-RT build will disable local interrupts and in an RT build will do nothing. (I suspect that RT kernels won't like it if we call spin_lock() while preemption is disabled.) > Is there such a function? Alan Stern