linux-kernel - Re: [PATCH v3 1/2] jiffies: Define secs_to

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Message-ID: <59a29847-2a3b-4aac-82f4-db9f1e52bb10@linux.microsoft.com>
Date: Thu, 31 Oct 2024 10:05:57 -0700
From: Easwar Hariharan <eahariha@...ux.microsoft.com>
To: Haiyang Zhang <haiyangz@...rosoft.com>, KY Srinivasan
 <kys@...rosoft.com>, Wei Liu <wei.liu@...nel.org>,
 Dexuan Cui <decui@...rosoft.com>,
 "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
 Anna-Maria Behnsen <anna-maria@...utronix.de>,
 Thomas Gleixner <tglx@...utronix.de>,
 Geert Uytterhoeven <geert@...ux-m68k.org>,
 Marcel Holtmann <marcel@...tmann.org>,
 Johan Hedberg <johan.hedberg@...il.com>,
 Luiz Augusto von Dentz <luiz.dentz@...il.com>,
 "linux-bluetooth@...r.kernel.org" <linux-bluetooth@...r.kernel.org>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 Praveen Kumar <kumarpraveen@...ux.microsoft.com>,
 Naman Jain <namjain@...ux.microsoft.com>
Cc: eahariha@...ux.microsoft.com, Michael Kelley <mhklinux@...look.com>,
 "Von Dentz, Luiz" <luiz.von.dentz@...el.com>
Subject: Re: [PATCH v3 1/2] jiffies: Define secs_to_jiffies()

On 10/31/2024 8:54 AM, Haiyang Zhang wrote:
> 
> 
>> -----Original Message-----
>> From: Easwar Hariharan <eahariha@...ux.microsoft.com>
>> Sent: Wednesday, October 30, 2024 1:48 PM
>> To: KY Srinivasan <kys@...rosoft.com>; Haiyang Zhang
>> <haiyangz@...rosoft.com>; Wei Liu <wei.liu@...nel.org>; Dexuan Cui
>> <decui@...rosoft.com>; linux-hyperv@...r.kernel.org; Anna-Maria Behnsen
>> <anna-maria@...utronix.de>; Thomas Gleixner <tglx@...utronix.de>; Geert
>> Uytterhoeven <geert@...ux-m68k.org>; Marcel Holtmann
>> <marcel@...tmann.org>; Johan Hedberg <johan.hedberg@...il.com>; Luiz
>> Augusto von Dentz <luiz.dentz@...il.com>; linux-
>> bluetooth@...r.kernel.org; linux-kernel@...r.kernel.org; Praveen Kumar
>> <kumarpraveen@...ux.microsoft.com>; Naman Jain
>> <namjain@...ux.microsoft.com>
>> Cc: Michael Kelley <mhklinux@...look.com>; Easwar Hariharan
>> <eahariha@...ux.microsoft.com>; Von Dentz, Luiz
>> <luiz.von.dentz@...el.com>
>> Subject: [PATCH v3 1/2] jiffies: Define secs_to_jiffies()
>>
>> secs_to_jiffies() is defined in hci_event.c and cannot be reused by
>> other call sites. Hoist it into the core code to allow conversion of the
>> ~1150 usages of msecs_to_jiffies() that either:
>> - use a multiplier value of 1000 or equivalently MSEC_PER_SEC, or
>> - have timeouts that are denominated in seconds (i.e. end in 000)
>>
>> This will also allow conversion of yet more sites that use (sec * HZ)
>> directly, and improve their readability.
>>
>> TO: K. Y. Srinivasan <kys@...rosoft.com>
>> TO: Haiyang Zhang <haiyangz@...rosoft.com>
>> TO: Wei Liu <wei.liu@...nel.org>
>> TO: Dexuan Cui <decui@...rosoft.com>
>> TO: linux-hyperv@...r.kernel.org
>> TO: Anna-Maria Behnsen <anna-maria@...utronix.de>
>> TO: Thomas Gleixner <tglx@...utronix.de>
>> TO: Geert Uytterhoeven <geert@...ux-m68k.org>
>> TO: Marcel Holtmann <marcel@...tmann.org>
>> TO: Johan Hedberg <johan.hedberg@...il.com>
>> TO: Luiz Augusto von Dentz <luiz.dentz@...il.com>
>> TO: linux-bluetooth@...r.kernel.org
>> TO: linux-kernel@...r.kernel.org
>> Suggested-by: Michael Kelley <mhklinux@...look.com>
>> Reviewed-by: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>
>> Signed-off-by: Easwar Hariharan <eahariha@...ux.microsoft.com>
>> ---
>>  include/linux/jiffies.h   | 12 ++++++++++++
>>  net/bluetooth/hci_event.c |  2 --
>>  2 files changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h
>> index
>> 1220f0fbe5bf9fb6c559b4efd603db3e97db9b65..e17c220ed56e587fd55fb9cf4a133a5
>> 3588af940 100644
>> --- a/include/linux/jiffies.h
>> +++ b/include/linux/jiffies.h
>> @@ -526,6 +526,18 @@ static __always_inline unsigned long
>> msecs_to_jiffies(const unsigned int m)
>>  	}
>>  }
>>
>> +/**
>> + * secs_to_jiffies: - convert seconds to jiffies
>> + * @_secs: time in seconds
>> + *
>> + * Conversion is done by simple multiplication with HZ
>> + * secs_to_jiffies() is defined as a macro rather than a static inline
>> + * function due to its potential application in struct initializers.
>> + *
>> + * Return: jiffies value
>> + */
>> +#define secs_to_jiffies(_secs) ((_secs) * HZ)
>> +
>>  extern unsigned long __usecs_to_jiffies(const unsigned int u);
>>  #if !(USEC_PER_SEC % HZ)
>>  static inline unsigned long _usecs_to_jiffies(const unsigned int u)
>> diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
>> index
>> 0bbad90ddd6f87e87c03859bae48a7901d39b634..7b35c58bbbeb79f2b50a02212771fb2
>> 83ba5643d 100644
>> --- a/net/bluetooth/hci_event.c
>> +++ b/net/bluetooth/hci_event.c
>> @@ -42,8 +42,6 @@
>>  #define ZERO_KEY "\x00\x00\x00\x00\x00\x00\x00\x00" \
>>  		 "\x00\x00\x00\x00\x00\x00\x00\x00"
>>
>> -#define secs_to_jiffies(_secs) msecs_to_jiffies((_secs) * 1000)
>> -
>>  /* Handle HCI Event packets */
>>
>>  static void *hci_ev_skb_pull(struct hci_dev *hdev, struct sk_buff *skb,
>>
>> --
>> 2.34.1
> 
> All looks good.
> But can you consider naming the macro as s2jiffy()? Just
> to be shorter, so after adopting this macro we don't have
> to split some lines for over 80 characters:)
> 
> Thanks,
> - Haiyang
> 

Thanks for the review! The patch introducing the macro has already been
accepted into timers/core in tip[1], so unfortunately I can't make that
change anymore. For readability considerations, I also find it better to
match the remaining APIs in the jiffies family, i.e. msecs_to_jiffies(),
nsecs_to_jiffies(), usecs_to_jiffies().

[1] https://git.kernel.org/tip/b35108a51cf7bab58d7eace1267d7965978bcdb8

Thanks,
Easwar