13 Aug
2022
13 Aug
'22
1:43 p.m.
Hi!
From: Sebastian Andrzej Siewior bigeasy@linutronix.de
[ Upstream commit cf634d540a29018e8d69ab1befb7e08182bc6594 ]
i_dir_seq is a sequence counter with a lock which is represented by the lowest bit. The writer atomically updates the counter which ensures that it can be modified by only one writer at a time. This requires preemption to be disabled across the write side critical section.
On !PREEMPT_RT kernels this is implicit by the caller acquiring dentry::lock. On PREEMPT_RT kernels spin_lock() does not disable preemption
This should not be applied to 4.19 as CONFIG_PREEMPT_RT does not exist there.
Best regards, Pavel
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