netdev - Re: [PATCH v10 1/8] sched/core: Add __might_sleep

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Message-Id: <20250208.120103.2120997372702679311.fujita.tomonori@gmail.com>
Date: Sat, 08 Feb 2025 12:01:03 +0900 (JST)
From: FUJITA Tomonori <fujita.tomonori@...il.com>
To: david.laight.linux@...il.com, aliceryhl@...gle.com, boqun.feng@...il.com
Cc: fujita.tomonori@...il.com, linux-kernel@...r.kernel.org,
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Subject: Re: [PATCH v10 1/8] sched/core: Add __might_sleep_precision()

On Fri, 7 Feb 2025 18:12:58 +0000
David Laight <david.laight.linux@...il.com> wrote:

>>  static void print_preempt_disable_ip(int preempt_offset, unsigned long ip)
>>  {
>>  	if (!IS_ENABLED(CONFIG_DEBUG_PREEMPT))
>> @@ -8717,7 +8699,8 @@ static inline bool resched_offsets_ok(unsigned int offsets)
>>  	return nested == offsets;
>>  }
>>  
>> -void __might_resched(const char *file, int line, unsigned int offsets)
>> +static void __might_resched_precision(const char *file, int len, int line,
> 
> For clarity that ought to be file_len.

Yeah, I'll update.

>> +				      unsigned int offsets)
>>  {
>>  	/* Ratelimiting timestamp: */
>>  	static unsigned long prev_jiffy;
>> @@ -8740,8 +8723,10 @@ void __might_resched(const char *file, int line, unsigned int offsets)
>>  	/* Save this before calling printk(), since that will clobber it: */
>>  	preempt_disable_ip = get_preempt_disable_ip(current);
>>  
>> -	pr_err("BUG: sleeping function called from invalid context at %s:%d\n",
>> -	       file, line);
>> +	if (len < 0)
>> +		len = strlen(file);
> 
> No need for strlen(), just use a big number instead of -1.
> Anything bigger than a sane upper limit on the filename length will do.

Ah, that's right. Just passing the maximum precision (1<<15-1) works.

The precision specifies the maximum length. vsnprintf() always
iterates through a string until it reaches the maximum length or
encounters the null terminator. So strlen() here is useless.

Alice and Boqun, the above change is fine? Can I keep the tags?