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random.c ratelimits how much it warns about uninitialized urandom reads
using __ratelimit(). When the RNG is finally initialized, it prints the
number of missed messages due to ratelimiting.
It has been this way since that functionality was introduced back in
2018. Recently, cc1e127bfa95 ("random: remove ratelimiting for in-kernel
unseeded randomness") put a bit more stress on the urandom ratelimiting,
which teased out a bug in the implementation.
Specifically, when under pressure, __ratelimit() will print its own
message and reset the count back to 0, making the final message at the
end less useful. Secondly, it does so as a pr_warn(), which apparently
is undesirable for people's CI.
Fortunately, __ratelimit() has the RATELIMIT_MSG_ON_RELEASE flag exactly
for this purpose, so we set the flag.
Fixes: 4e00b339e264 ("random: rate limit unseeded randomness warnings")
Cc: stable@vger.kernel.org
Reported-by: Jon Hunter <jonathanh@nvidia.com>
Reported-by: Ron Economos <re@w6rz.net>
Tested-by: Ron Economos <re@w6rz.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
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The printk header file includes ratelimit_types.h for its __ratelimit()
based usage. It is required for the static initializer used in
printk_ratelimited(). It uses a raw_spinlock_t and includes the
spinlock_types.h.
PREEMPT_RT substitutes spinlock_t with a rtmutex based implementation and so
its spinlock_t implmentation (provided by spinlock_rt.h) includes rtmutex.h and
atomic.h which leads to recursive includes where defines are missing.
By including only the raw_spinlock_t defines it avoids the atomic.h
related includes at this stage.
An example on powerpc:
| CALL scripts/atomic/check-atomics.sh
|In file included from include/linux/bug.h:5,
| from include/linux/page-flags.h:10,
| from kernel/bounds.c:10:
|arch/powerpc/include/asm/page_32.h: In function âclear_pageâ:
|arch/powerpc/include/asm/bug.h:87:4: error: implicit declaration of function â=80=98__WARNâ=80=99 [-Werror=3Dimplicit-function-declaration]
| 87 | __WARN(); \
| | ^~~~~~
|arch/powerpc/include/asm/page_32.h:48:2: note: in expansion of macro âWARN_ONâ=99
| 48 | WARN_ON((unsigned long)addr & (L1_CACHE_BYTES - 1));
| | ^~~~~~~
|arch/powerpc/include/asm/bug.h:58:17: error: invalid application of âsizeofâ=99 to incomplete type âstruct bug_entryâ=99
| 58 | "i" (sizeof(struct bug_entry)), \
| | ^~~~~~
|arch/powerpc/include/asm/bug.h:89:3: note: in expansion of macro âBUG_ENTRYâ=99
| 89 | BUG_ENTRY(PPC_TLNEI " %4, 0", \
| | ^~~~~~~~~
|arch/powerpc/include/asm/page_32.h:48:2: note: in expansion of macro âWARN_ONâ=99
| 48 | WARN_ON((unsigned long)addr & (L1_CACHE_BYTES - 1));
| | ^~~~~~~
|In file included from arch/powerpc/include/asm/ptrace.h:298,
| from arch/powerpc/include/asm/hw_irq.h:12,
| from arch/powerpc/include/asm/irqflags.h:12,
| from include/linux/irqflags.h:16,
| from include/asm-generic/cmpxchg-local.h:6,
| from arch/powerpc/include/asm/cmpxchg.h:526,
| from arch/powerpc/include/asm/atomic.h:11,
| from include/linux/atomic.h:7,
| from include/linux/rwbase_rt.h:6,
| from include/linux/rwlock_types.h:55,
| from include/linux/spinlock_types.h:74,
| from include/linux/ratelimit_types.h:7,
| from include/linux/printk.h:10,
| from include/asm-generic/bug.h:22,
| from arch/powerpc/include/asm/bug.h:109,
| from include/linux/bug.h:5,
| from include/linux/page-flags.h:10,
| from kernel/bounds.c:10:
|include/linux/thread_info.h: In function â=80=98copy_overflowâ=80=99:
|include/linux/thread_info.h:210:2: error: implicit declaration of function â=80=98WARNâ=80=99 [-Werror=3Dimplicit-function-declaration]
| 210 | WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);
| | ^~~~
The WARN / BUG include pulls in printk.h and then ptrace.h expects WARN
(from bug.h) which is not yet complete. Even hw_irq.h has WARN_ON()
statements.
On POWERPC64 there are missing atomic64 defines while building 32bit
VDSO:
| VDSO32C arch/powerpc/kernel/vdso32/vgettimeofday.o
|In file included from include/linux/atomic.h:80,
| from include/linux/rwbase_rt.h:6,
| from include/linux/rwlock_types.h:55,
| from include/linux/spinlock_types.h:74,
| from include/linux/ratelimit_types.h:7,
| from include/linux/printk.h:10,
| from include/linux/kernel.h:19,
| from arch/powerpc/include/asm/page.h:11,
| from arch/powerpc/include/asm/vdso/gettimeofday.h:5,
| from include/vdso/datapage.h:137,
| from lib/vdso/gettimeofday.c:5,
| from <command-line>:
|include/linux/atomic-arch-fallback.h: In function âarch_atomic64_incâ=99:
|include/linux/atomic-arch-fallback.h:1447:2: error: implicit declaration of function âarch_atomic64_addâ; did you mean âarch_atomic_addâ? [-Werror=3Dimpl
|icit-function-declaration]
| 1447 | arch_atomic64_add(1, v);
| | ^~~~~~~~~~~~~~~~~
| | arch_atomic_add
The generic fallback is not included, atomics itself are not used. If
kernel.h does not include printk.h then it comes later from the bug.h
include.
Allow asm/spinlock_types.h to be included from
linux/spinlock_types_raw.h.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211129174654.668506-12-bigeasy@linutronix.de
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