Re: [PATCH v2 2/2] bus: mhi: host: Take irqsave lock after TRE is generated

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]


On 9/24/2023 10:08 PM, Qiang Yu wrote:

On 9/22/2023 10:50 PM, Jeffrey Hugo wrote:
On 9/13/2023 2:47 AM, Qiang Yu wrote:
From: Hemant Kumar <quic_hemantk@xxxxxxxxxxx>

Take irqsave lock after TRE is generated to avoid deadlock due to core
getting interrupts enabled as local_bh_enable must not be called with
irqs disabled based on upstream patch.

Where is local_bh_enable() being called?  What patch?  What is upstream of the codebase you submitted this to?  Why is it safe to call mhi_gen_tre() without the lock?

This patch is to fix the issue included by  "[PATCH v2 1/2] bus: mhi: host: Add spinlock to protect WP access when queueing TREs". In that patch, we add write_lock_bh/write_unlock_bh in mhi_gen_tre().

However, before mhi_gen_tre() is invoked, mhi_cntrl->pm_lock is getted, line 1125, and it is a spin lock. So it becomes we want to get and release bh lock after spin lock.  __local_bh_enable_ip is called as part of write_unlock_bh

and local_bh_enable. When CONFIG_TRACE_IRQFLAGS is enabled, irq will be enabled once __local_bh_enable_ip is called. The commit message is not clear and confusing, will change it in [patch v3].

In addition to clarifying the commit message, I recommend looking at adding this to the other patch. It seems very odd to review a series where one patch introduces a known issue, and a following patch corrects that issue. It would be better to not introduce the issue in the first place.

[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [Linux for Sparc]     [IETF Annouce]     [Security]     [Bugtraq]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]

  Powered by Linux