Re: [PATCH 05/10] hwrng: stm32 - rework error handling in stm32_rng_read()

kernel test robot
2023-09-08T21:49:37Z

Hi Gatien,

kernel test robot noticed the following build warnings:

[auto build test WARNING on atorgue-stm32/stm32-next]
[also build test WARNING on robh/for-next herbert-crypto-2.6/master herbert-cryptodev-2.6/master linus/master v6.5 next-20230908]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url: https://github.com/intel-lab-lkp/linux/commits/Gatien-Chevallier/dt-bindings-rng-introduce-new-compatible-for-STM32MP13x/20230909-005611
base: https://git.kernel.org/pub/scm/linux/kernel/git/atorgue/stm32.git stm32-next
patch link: https://lore.kernel.org/r/20230908165120.730867-6-gatien.chevallier%40foss.st.com
patch subject: [PATCH 05/10] hwrng: stm32 - rework error handling in stm32_rng_read()
config: hexagon-randconfig-002-20230909 (https://download.01.org/0day-ci/archive/20230909/202309090508.CyBIfKeu-lkp@intel.com/config)
compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project.git 4a5ac14ee968ff0ad5d2cc1ffa0299048db4c88a)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20230909/202309090508.CyBIfKeu-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@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202309090508.CyBIfKeu-lkp@intel.com/

All warnings (new ones prefixed by >>):

In file included from drivers/char/hw_random/stm32-rng.c:9:
In file included from include/linux/io.h:13:
In file included from arch/hexagon/include/asm/io.h:334:
include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
547 | val = __raw_readb(PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
560 | val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
37 | #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
| ^
In file included from drivers/char/hw_random/stm32-rng.c:9:
In file included from include/linux/io.h:13:
In file included from arch/hexagon/include/asm/io.h:334:
include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
573 | val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
35 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
| ^
In file included from drivers/char/hw_random/stm32-rng.c:9:
In file included from include/linux/io.h:13:
In file included from arch/hexagon/include/asm/io.h:334:
include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
584 | __raw_writeb(value, PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
594 | __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
604 | __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
>> drivers/char/hw_random/stm32-rng.c:210:35: warning: left operand of comma operator has no effect [-Wunused-value]
210 | if (WARN_ON(sr & RNG_SR_CEIS), "RNG clock too slow - %x\n", sr)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:55:57: note: expanded from macro 'if'
55 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
| ^~~~~~~~~~~
include/linux/compiler.h:57:52: note: expanded from macro '__trace_if_var'
57 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
| ^~~~
>> drivers/char/hw_random/stm32-rng.c:210:35: warning: left operand of comma operator has no effect [-Wunused-value]
210 | if (WARN_ON(sr & RNG_SR_CEIS), "RNG clock too slow - %x\n", sr)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:55:57: note: expanded from macro 'if'
55 | #define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
| ^~~~~~~~~~~
include/linux/compiler.h:57:86: note: expanded from macro '__trace_if_var'
57 | #define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
| ^~~~
include/linux/compiler.h:68:3: note: expanded from macro '__trace_if_value'
68 | (cond) ? \
| ^~~~
8 warnings generated.

vim +210 drivers/char/hw_random/stm32-rng.c

162
163
164 static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
165 {
166 struct stm32_rng_private *priv = container_of(rng, struct stm32_rng_private, rng);
167 unsigned int i = 0;
168 int retval = 0, err = 0;
169 u32 sr;
170
171 pm_runtime_get_sync((struct device *) priv->rng.priv);
172
173 if (readl_relaxed(priv->base + RNG_SR) & RNG_SR_SEIS)
174 stm32_rng_conceal_seed_error(rng);
175
176 while (max >= sizeof(u32)) {
177 sr = readl_relaxed(priv->base + RNG_SR);
178 /*
179 * Manage timeout which is based on timer and take
180 * care of initial delay time when enabling the RNG.
181 */
182 if (!sr && wait) {
183 err = readl_relaxed_poll_timeout_atomic(priv->base
184 + RNG_SR,
185 sr, sr,
186 10, 50000);
187 if (err) {
188 dev_err((struct device *)priv->rng.priv,
189 "%s: timeout %x!\n", __func__, sr);
190 break;
191 }
192 } else if (!sr) {
193 /* The FIFO is being filled up */
194 break;
195 }
196
197 if (sr != RNG_SR_DRDY) {
198 if (sr & RNG_SR_SEIS) {
199 err = stm32_rng_conceal_seed_error(rng);
200 i++;
201 if (err && i > RNG_NB_RECOVER_TRIES) {
202 dev_err((struct device *)priv->rng.priv,
203 "Couldn't recover from seed error\n");
204 return -ENOTRECOVERABLE;
205 }
206
207 continue;
208 }
209
> 210 if (WARN_ON(sr & RNG_SR_CEIS), "RNG clock too slow - %x\n", sr)
211 writel_relaxed(0, priv->base + RNG_SR);
212 }
213
214 /* Late seed error case: DR being 0 is an error status */
215 *(u32 *)data = readl_relaxed(priv->base + RNG_DR);
216 if (!*(u32 *)data) {
217 err = stm32_rng_conceal_seed_error(rng);
218 i++;
219 if (err && i > RNG_NB_RECOVER_TRIES) {
220 dev_err((struct device *)priv->rng.priv,
221 "Couldn't recover from seed error");
222 return -ENOTRECOVERABLE;
223 }
224
225 continue;
226 }
227
228 i = 0;
229 retval += sizeof(u32);
230 data += sizeof(u32);
231 max -= sizeof(u32);
232 }
233
234 pm_runtime_mark_last_busy((struct device *) priv->rng.priv);
235 pm_runtime_put_sync_autosuspend((struct device *) priv->rng.priv);
236
237 return retval || !wait ? retval : -EIO;
238 }
239

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