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Message-ID: <e8f6137d-ad2c-4b06-8eb2-cd200fbb1af2@paulmck-laptop>
Date: Mon, 30 Sep 2024 09:10:27 -0700
From: "Paul E. McKenney" <paulmck@...nel.org>
To: kernel test robot <lkp@...el.com>
Cc: oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org,
linux-snps-arc@...ts.infradead.org
Subject: Re: arch/arc/kernel/smp.c:267:18: sparse: sparse: cast removes
address space '__percpu' of expression
On Wed, Sep 25, 2024 at 01:40:45PM +0800, kernel test robot wrote:
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: 684a64bf32b6e488004e0ad7f0d7e922798f65b6
> commit: f2519d4d4fc4d36f2b58c5614357de9f5b4032fc ARC: Emulate one-byte cmpxchg
> date: 12 days ago
> config: arc-randconfig-r123-20240925 (https://download.01.org/0day-ci/archive/20240925/202409251336.ToC0TvWB-lkp@intel.com/config)
> compiler: arc-elf-gcc (GCC) 13.2.0
> reproduce: (https://download.01.org/0day-ci/archive/20240925/202409251336.ToC0TvWB-lkp@intel.com/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@...el.com>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202409251336.ToC0TvWB-lkp@intel.com/
>
> sparse warnings: (new ones prefixed by >>)
> arch/arc/kernel/smp.c:252:48: sparse: sparse: incorrect type in initializer (different address spaces) @@ expected unsigned long [noderef] __percpu *ipi_data_ptr @@ got unsigned long * @@
> arch/arc/kernel/smp.c:252:48: sparse: expected unsigned long [noderef] __percpu *ipi_data_ptr
> arch/arc/kernel/smp.c:252:48: sparse: got unsigned long *
> arch/arc/kernel/smp.c:267:18: sparse: sparse: incorrect type in argument 1 (different address spaces) @@ expected void const volatile *v @@ got unsigned long [noderef] __percpu *__ai_ptr @@
> arch/arc/kernel/smp.c:267:18: sparse: expected void const volatile *v
> arch/arc/kernel/smp.c:267:18: sparse: got unsigned long [noderef] __percpu *__ai_ptr
> >> arch/arc/kernel/smp.c:267:18: sparse: sparse: cast removes address space '__percpu' of expression
> >> arch/arc/kernel/smp.c:267:18: sparse: sparse: cast removes address space '__percpu' of expression
I could "fix" this using __force. Is that a reasonable approach?
If I don't hear otherwise, I will take that approach.
Thanx, Paul
> arch/arc/kernel/smp.c:401:72: sparse: sparse: incorrect type in argument 4 (different address spaces) @@ expected void [noderef] __percpu *percpu_dev_id @@ got int *dev @@
> arch/arc/kernel/smp.c:401:72: sparse: expected void [noderef] __percpu *percpu_dev_id
> arch/arc/kernel/smp.c:401:72: sparse: got int *dev
> arch/arc/kernel/smp.c:265:30: sparse: sparse: dereference of noderef expression
>
> vim +/__percpu +267 arch/arc/kernel/smp.c
>
> 41195d236e8445 Vineet Gupta 2013-01-18 249
> ddf84433f411b6 Vineet Gupta 2013-11-25 250 static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
> 41195d236e8445 Vineet Gupta 2013-01-18 251 {
> f2a4aa5646687f Vineet Gupta 2013-11-26 252 unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 253 unsigned long old, new;
> 41195d236e8445 Vineet Gupta 2013-01-18 254 unsigned long flags;
> 41195d236e8445 Vineet Gupta 2013-01-18 255
> f2a4aa5646687f Vineet Gupta 2013-11-26 256 pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);
> f2a4aa5646687f Vineet Gupta 2013-11-26 257
> 41195d236e8445 Vineet Gupta 2013-01-18 258 local_irq_save(flags);
> 41195d236e8445 Vineet Gupta 2013-01-18 259
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 260 /*
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 261 * Atomically write new msg bit (in case others are writing too),
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 262 * and read back old value
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 263 */
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 264 do {
> c6ed4d84a2c49d Bang Li 2022-03-19 265 new = old = *ipi_data_ptr;
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 266 new |= 1U << msg;
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 @267 } while (cmpxchg(ipi_data_ptr, old, new) != old);
> 41195d236e8445 Vineet Gupta 2013-01-18 268
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 269 /*
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 270 * Call the platform specific IPI kick function, but avoid if possible:
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 271 * Only do so if there's no pending msg from other concurrent sender(s).
> 82a423053eb3cf Changcheng Deng 2021-08-14 272 * Otherwise, receiver will see this msg as well when it takes the
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 273 * IPI corresponding to that msg. This is true, even if it is already in
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 274 * IPI handler, because !@old means it has not yet dequeued the msg(s)
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 275 * so @new msg can be a free-loader
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 276 */
> d8e8c7dda11f5d Vineet Gupta 2013-11-28 277 if (plat_smp_ops.ipi_send && !old)
> ddf84433f411b6 Vineet Gupta 2013-11-25 278 plat_smp_ops.ipi_send(cpu);
> 41195d236e8445 Vineet Gupta 2013-01-18 279
> 41195d236e8445 Vineet Gupta 2013-01-18 280 local_irq_restore(flags);
> 41195d236e8445 Vineet Gupta 2013-01-18 281 }
> 41195d236e8445 Vineet Gupta 2013-01-18 282
>
> :::::: The code at line 267 was first introduced by commit
> :::::: d8e8c7dda11f5d5cf90495f2e89d917a83509bc0 ARC: [SMP] optimize IPI send and receive
>
> :::::: TO: Vineet Gupta <vgupta@...opsys.com>
> :::::: CC: Vineet Gupta <vgupta@...opsys.com>
>
> --
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki
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