FAILED: patch "[PATCH] random: check for signal_pending() outside of need_resched()" failed to apply to 5.16-stable tree
Subsystems (2)
[email protected]
maintainerThe patch below does not apply to the 5.16-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 1448769c9cdb69ad65287f4f7ab58bc5f2f5d7ba Mon Sep 17 00:00:00 2001
From: Jann Horn <[email protected]>
Date: Tue, 5 Apr 2022 18:39:31 +0200
Subject: [PATCH] random: check for signal_pending() outside of need_resched()
check
signal_pending() checks TIF_NOTIFY_SIGNAL and TIF_SIGPENDING, which signal that the task should bail out of the syscall when possible. This is a separate concept from need_resched(), which checks TIF_NEED_RESCHED, signaling that the task should preempt.
In particular, with the current code, the signal_pending() bailout probably won't work reliably.
Change this to look like other functions that read lots of data, such as read_zero().
drivers/char/random.c +2 -2
@@ -549,13 +549,13 @@ static ssize_t get_random_bytes_user(void __user *buf, size_t nbytes) } do { - if (large_request && need_resched()) { + if (large_request) { if (signal_pending(current)) { if (!ret) ret = -ERESTARTSYS; break; } - schedule(); + cond_resched(); } chacha20_block(chacha_state, output);