linux-kernel - Re: [PATCH 1/2] target: drop spin_lock_assert() + irqs

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Date:   Mon, 26 Mar 2018 11:13:59 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "bigeasy@...utronix.de" <bigeasy@...utronix.de>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        "nab@...ux-iscsi.org" <nab@...ux-iscsi.org>,
        Bart Van Assche <Bart.VanAssche@....com>,
        "acme@...nel.org" <acme@...nel.org>,
        "daniel@...stot.me" <daniel@...stot.me>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "williams@...hat.com" <williams@...hat.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "lclaudio@...hat.com" <lclaudio@...hat.com>,
        "target-devel@...r.kernel.org" <target-devel@...r.kernel.org>,
        "linux-rt-users@...r.kernel.org" <linux-rt-users@...r.kernel.org>
Subject: Re: [PATCH 1/2] target: drop spin_lock_assert() + irqs_disabled()
 combo checks

On Fri, 23 Mar 2018 18:17:36 +0100
"bigeasy@...utronix.de" <bigeasy@...utronix.de> wrote:

> There are a few functions which check for if the lock is held
> (spin_lock_assert()) and the interrupts are disabled (irqs_disabled()).
> >From looking at the code, each function is static, the caller is near by  
> and does spin_lock_irq|safe(). As Linus puts it:
> 
> |It's not like this is some function that is exported to random users,
> |and we should check that the calling convention is right.
> |
> |This looks like "it may have been useful during coding to document
> |things, but it's not useful long-term".
> 
> Remove those checks.
> 
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> ---
>  drivers/target/target_core_tmr.c       | 2 --
>  drivers/target/target_core_transport.c | 6 ------
>  2 files changed, 8 deletions(-)
> 
> diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
> index 9c7bc1ca341a..3d35dad1de2c 100644
> --- a/drivers/target/target_core_tmr.c
> +++ b/drivers/target/target_core_tmr.c

Can you add a comment above the functions though?

/* Expects to have se_cmd->se_sess->sess_cmd_lock held */

> @@ -114,8 +114,6 @@ static bool __target_check_io_state(struct se_cmd *se_cmd,
>  {
>  	struct se_session *sess = se_cmd->se_sess;
>  
> -	assert_spin_locked(&sess->sess_cmd_lock);
> -	WARN_ON_ONCE(!irqs_disabled());
>  	/*
>  	 * If command already reached CMD_T_COMPLETE state within
>  	 * target_complete_cmd() or CMD_T_FABRIC_STOP due to shutdown,
> diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> index 74b646f165d4..2c3ddb3a4124 100644
> --- a/drivers/target/target_core_transport.c
> +++ b/drivers/target/target_core_transport.c

/* Expects to have cmd->t_state_lock held */

> @@ -2954,9 +2954,6 @@ __transport_wait_for_tasks(struct se_cmd *cmd, bool fabric_stop,
>  	__acquires(&cmd->t_state_lock)
>  {
>  
> -	assert_spin_locked(&cmd->t_state_lock);
> -	WARN_ON_ONCE(!irqs_disabled());
> -
>  	if (fabric_stop)
>  		cmd->transport_state |= CMD_T_FABRIC_STOP;
>  

/* Expects to have cmd->t_state_lock held */

> @@ -3241,9 +3238,6 @@ static int __transport_check_aborted_status(struct se_cmd *cmd, int send_status)
>  {
>  	int ret;
>  
> -	assert_spin_locked(&cmd->t_state_lock);
> -	WARN_ON_ONCE(!irqs_disabled());
> -
>  	if (!(cmd->transport_state & CMD_T_ABORTED))
>  		return 0;
>  	/*

-- Steve