From: Christoph Hellwig <hch@infradead.org>
To: Haren Myneni <haren@linux.ibm.com>
Cc: mpe@ellerman.id.au, devicetree@vger.kernel.org,
mikey@neuling.org, herbert@gondor.apana.org.au,
npiggin@gmail.com, hch@infradead.org, sukadev@linux.vnet.ibm.com,
linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH V2 07/13] powerpc/vas: Take reference to PID and mm for user space windows
Date: Thu, 12 Dec 2019 05:02:48 -0800 [thread overview]
Message-ID: <20191212130248.GE3381@infradead.org> (raw)
In-Reply-To: <1575862366.16318.24.camel@hbabu-laptop>
> + if (txwin->user_win) {
> + /*
> + * Window opened by child thread may not be closed when
> + * it exits. So take reference to its pid and release it
> + * when the window is free by parent thread.
> + * Acquire a reference to the task's pid to make sure
> + * pid will not be re-used.
> + */
> + txwin->pid = get_task_pid(current, PIDTYPE_PID);
> + /*
> + * Acquire a reference to the task's mm.
> + */
> + txwin->mm = get_task_mm(current);
> +
> + if (txwin->mm) {
> + mmput(txwin->mm);
> + mmgrab(txwin->mm);
Doesn't the mmgrab need to come before the mmput?
> + mm_context_add_copro(txwin->mm);
> + } else {
> + put_pid(txwin->pid);
> + pr_err("VAS: pid(%d): mm_struct is not found\n",
> + current->pid);
> + rc = -EPERM;
> + goto free_window;
> + }
Also the code is much easier to follow if you handle the error
first and avoid the else:
txwin->mm = get_task_mm(current);
if (!txwin->mm) {
put_pid(txwin->pid);
pr_err("VAS: pid(%d): mm_struct is not found\n",
current->pid);
rc = -EPERM;
goto free_window;
}
mmgrab(txwin->mm);
mmput(txwin->mm);
Also don't you need to take a reference to the struct pid for the
tgid as well?
next prev parent reply other threads:[~2019-12-12 13:02 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-09 3:18 [PATCH V2 00/13] powerpc/vas: Page fault handling for user space NX requests Haren Myneni
2019-12-09 3:26 ` [PATCH V2 01/13] powerpc/vas: Describe vas-port and interrupts properties Haren Myneni
2019-12-09 3:27 ` [PATCH V2 02/13] powerpc/vas: Define nx_fault_stamp in coprocessor_request_block Haren Myneni
2019-12-09 3:29 ` [PATCH V2 03/13] powerpc/vas: Read interrupts and vas-port device tree properties Haren Myneni
2019-12-09 3:30 ` [PATCH V2 04/13] powerpc/vas: Setup fault window per VAS instance Haren Myneni
2019-12-12 12:55 ` Christoph Hellwig
2019-12-09 3:31 ` [PATCH V2 05/13] powerpc/vas: Setup thread IRQ handler " Haren Myneni
2019-12-12 12:59 ` Christoph Hellwig
2019-12-09 3:32 ` [PATCH V2 06/13] powerpc/vas: Register NX with fault window ID and IRQ port value Haren Myneni
2019-12-09 3:32 ` [PATCH V2 07/13] powerpc/vas: Take reference to PID and mm for user space windows Haren Myneni
2019-12-12 13:02 ` Christoph Hellwig [this message]
2019-12-17 5:35 ` Haren Myneni
2019-12-09 3:33 ` [PATCH V2 08/13] powerpc/vas: Update CSB and notify process for fault CRBs Haren Myneni
2019-12-12 13:07 ` Christoph Hellwig
2019-12-09 3:34 ` [PATCH V2 09/13] powerpc/vas: Print CRB and FIFO values Haren Myneni
2019-12-09 3:34 ` [PATCH V2 10/13] powerpc/vas: Do not use default credits for receive window Haren Myneni
2019-12-09 3:35 ` [PATCH V2 11/13] powerpc/vas: Return credits after handling fault Haren Myneni
2019-12-09 3:36 ` [PATCH V2 12/13] powerpc/vas: Display process stuck message Haren Myneni
2019-12-09 3:37 ` [PATCH V2 13/13] powerpc/vas: Free send window in VAS instance after credits returned Haren Myneni
2019-12-09 5:37 ` [PATCH V2 00/13] powerpc/vas: Page fault handling for user space NX requests Christophe Leroy
2019-12-09 8:38 ` Segher Boessenkool
2019-12-12 5:05 ` Haren Myneni
2019-12-12 5:38 ` Haren Myneni
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