linux-kernel - Re: [PATCH v2] powerpc/fadump: return error when fadump registration fails

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Message-Id: <94a13143-542f-8894-234f-755248f21c77@linux.vnet.ibm.com>
Date:   Thu, 1 Jun 2017 15:30:27 +0530
From:   Hari Bathini <hbathini@...ux.vnet.ibm.com>
To:     Michal Suchanek <msuchanek@...e.de>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Colin Ian King <colin.king@...onical.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] powerpc/fadump: return error when fadump registration
 fails



On Saturday 27 May 2017 09:16 PM, Michal Suchanek wrote:
>   - log an error message when registration fails and no error code listed
>   in the switch is returned
>   - translate the hv error code to posix error code and return it from
>   fw_register
>   - return the posix error code from fw_register to the process writing
>   to sysfs
>   - return EEXIST on re-registration
>   - return success on deregistration when fadump is not registered
>   - return ENODEV when no memory is reserved for fadump
>
> Signed-off-by: Michal Suchanek <msuchanek@...e.de>

With the below change write to /sys/kernel/fadump_registered returns 
error appropriately.

Tested-by: Hari Bathini <hbathini@...ux.vnet.ibm.com>

> ---
> v2: fix return in register_fadump()
> ---
>   arch/powerpc/kernel/fadump.c | 24 ++++++++++++++++--------
>   1 file changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
> index 2fa582092d42..83421e0a774b 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -398,9 +398,9 @@ static int __init early_fadump_param(char *p)
>   }
>   early_param("fadump", early_fadump_param);
>
> -static void register_fw_dump(struct fadump_mem_struct *fdm)
> +static int register_fw_dump(struct fadump_mem_struct *fdm)
>   {
> -	int rc;
> +	int rc, err;
>   	unsigned int wait_time;
>
>   	pr_debug("Registering for firmware-assisted kernel dump...\n");
> @@ -417,7 +417,12 @@ static void register_fw_dump(struct fadump_mem_struct *fdm)
>
>   	} while (wait_time);
>
> +	err = -EIO;
>   	switch (rc) {
> +	default:
> +		printk(KERN_ERR "Failed to register firmware-assisted kernel"
> +			" dump. Unknown Error(%d).\n", rc);
> +		break;
>   	case -1:
>   		printk(KERN_ERR "Failed to register firmware-assisted kernel"
>   			" dump. Hardware Error(%d).\n", rc);
> @@ -425,18 +430,22 @@ static void register_fw_dump(struct fadump_mem_struct *fdm)
>   	case -3:
>   		printk(KERN_ERR "Failed to register firmware-assisted kernel"
>   			" dump. Parameter Error(%d).\n", rc);
> +		err = -EINVAL;
>   		break;
>   	case -9:
>   		printk(KERN_ERR "firmware-assisted kernel dump is already "
>   			" registered.");
>   		fw_dump.dump_registered = 1;
> +		err = -EEXIST;
>   		break;
>   	case 0:
>   		printk(KERN_INFO "firmware-assisted kernel dump registration"
>   			" is successful\n");
>   		fw_dump.dump_registered = 1;
> +		err = 0;
>   		break;
>   	}
> +	return err;
>   }
>
>   void crash_fadump(struct pt_regs *regs, const char *str)
> @@ -977,7 +986,7 @@ static unsigned long init_fadump_header(unsigned long addr)
>   	return addr;
>   }
>
> -static void register_fadump(void)
> +static int register_fadump(void)
>   {
>   	unsigned long addr;
>   	void *vaddr;
> @@ -987,7 +996,7 @@ static void register_fadump(void)
>   	 * assisted dump.
>   	 */
>   	if (!fw_dump.reserve_dump_area_size)
> -		return;
> +		return -ENODEV;
>
>   	fadump_setup_crash_memory_ranges();
>
> @@ -1000,7 +1009,7 @@ static void register_fadump(void)
>   	fadump_create_elfcore_headers(vaddr);
>
>   	/* register the future kernel dump with firmware. */
> -	register_fw_dump(&fdm);
> +	return register_fw_dump(&fdm);
>   }
>
>   static int fadump_unregister_dump(struct fadump_mem_struct *fdm)
> @@ -1182,7 +1191,6 @@ static ssize_t fadump_register_store(struct kobject *kobj,
>   	switch (buf[0]) {
>   	case '0':
>   		if (fw_dump.dump_registered == 0) {
> -			ret = -EINVAL;
>   			goto unlock_out;
>   		}
>   		/* Un-register Firmware-assisted dump */
> @@ -1190,11 +1198,11 @@ static ssize_t fadump_register_store(struct kobject *kobj,
>   		break;
>   	case '1':
>   		if (fw_dump.dump_registered == 1) {
> -			ret = -EINVAL;
> +			ret = -EEXIST;
>   			goto unlock_out;
>   		}
>   		/* Register Firmware-assisted dump */
> -		register_fadump();
> +		ret = register_fadump();
>   		break;
>   	default:
>   		ret = -EINVAL;