Re: [PATCH 1/2] cleanup: move it back from util_lib/elf_info.c

[lijiang <lijiang@redhat.com>]

在 2019年08月22日 16:51, Simon Horman 写道:
> Hi Lianbo,
> 
> I like where this patch is going but I would like to request a few changes.
> Please see comments inline.
> 

Thanks for your comment, Simon.

> On Thu, Aug 15, 2019 at 11:37:55AM +0800, Lianbo Jiang wrote:
>> Some code related to vmcore-dmesg.c is put into the util_lib, which
>> is not very reasonable, so lets move it back and tidy up those code.
>>
>> In addition, that will also help to limit the size of vmcore-dmesg.txt.
>>
>> Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
>> ---
>>  kexec/arch/arm64/kexec-arm64.c |  2 +-
>>  util_lib/elf_info.c            | 73 ++++++++--------------------------
>>  util_lib/include/elf_info.h    |  8 +++-
>>  vmcore-dmesg/vmcore-dmesg.c    | 44 +++++++++++++++++---
>>  4 files changed, 61 insertions(+), 66 deletions(-)
>>
>> diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
>> index eb3a3a37307c..6ad3b0a134b3 100644
>> --- a/kexec/arch/arm64/kexec-arm64.c
>> +++ b/kexec/arch/arm64/kexec-arm64.c
>> @@ -889,7 +889,7 @@ int get_phys_base_from_pt_load(unsigned long *phys_offset)
>>  		return EFAILED;
>>  	}
>>  
>> -	read_elf_kcore(fd);
>> +	read_elf(fd);
>>  
>>  	for (i = 0; get_pt_load(i,
>>  		    &phys_start, NULL, &virt_start, NULL);
>> diff --git a/util_lib/elf_info.c b/util_lib/elf_info.c
>> index 90a3b21662e7..2f254e972721 100644
>> --- a/util_lib/elf_info.c
>> +++ b/util_lib/elf_info.c
>> @@ -20,7 +20,6 @@
>>  /* The 32bit and 64bit note headers make it clear we don't care */
>>  typedef Elf32_Nhdr Elf_Nhdr;
>>  
>> -static const char *fname;
>>  static Elf64_Ehdr ehdr;
>>  static Elf64_Phdr *phdr;
>>  static int num_pt_loads;
>> @@ -120,8 +119,8 @@ void read_elf32(int fd)
>>  
>>  	ret = pread(fd, &ehdr32, sizeof(ehdr32), 0);
>>  	if (ret != sizeof(ehdr32)) {
>> -		fprintf(stderr, "Read of Elf header from %s failed: %s\n",
>> -			fname, strerror(errno));
>> +		fprintf(stderr, "Read of Elf header failed in %s: %s\n",
>> +				__func__, strerror(errno));
> 
> I'm not sure of the merit of changing the loging output.

The variable 'fname' is defined two twice, the first definition is in the vmcore-dmesg.c, and the
second definition is in the elf_info.c. That is confused although it's a static type, because i do
not see the place where the value of variable 'fname' is set in elf_info.c. So i guess that it should
be a same variable within the vmcore-dmesg.c and also need to clean up.

> And moreover I don't think it belongs in this patch
> as it doesn't seem related to the other changes.
> 

Good question. I will consider how to clean up. Probably, it should be a separate patch.

>>  		exit(10);
>>  	}
>>  
>> @@ -193,8 +192,8 @@ void read_elf64(int fd)
>>  
>>  	ret = pread(fd, &ehdr64, sizeof(ehdr64), 0);
>>  	if (ret < 0 || (size_t)ret != sizeof(ehdr)) {
>> -		fprintf(stderr, "Read of Elf header from %s failed: %s\n",
>> -			fname, strerror(errno));
>> +		fprintf(stderr, "Read of Elf header failed in %s: %s\n",
>> +				__func__, strerror(errno));
>>  		exit(10);
>>  	}
>>  
>> @@ -531,19 +530,7 @@ static int32_t read_file_s32(int fd, uint64_t addr)
>>  	return read_file_u32(fd, addr);
>>  }
>>  
>> -static void write_to_stdout(char *buf, unsigned int nr)
>> -{
>> -	ssize_t ret;
>> -
>> -	ret = write(STDOUT_FILENO, buf, nr);
>> -	if (ret != nr) {
>> -		fprintf(stderr, "Failed to write out the dmesg log buffer!:"
>> -			" %s\n", strerror(errno));
>> -		exit(54);
>> -	}
>> -}
>> -
>> -static void dump_dmesg_legacy(int fd)
>> +void dump_dmesg_legacy(int fd, handler_t handler)
>>  {
>>  	uint64_t log_buf, log_buf_offset;
>>  	unsigned log_end, logged_chars, log_end_wrapped;
>> @@ -604,7 +591,7 @@ static void dump_dmesg_legacy(int fd)
>>  	 */
>>  	logged_chars = log_end < log_buf_len ? log_end : log_buf_len;
>>  
>> -	write_to_stdout(buf + (log_buf_len - logged_chars), logged_chars);
>> +	handler(buf + (log_buf_len - logged_chars), logged_chars);
>>  }
>>  
>>  static inline uint16_t struct_val_u16(char *ptr, unsigned int offset)
>> @@ -623,7 +610,7 @@ static inline uint64_t struct_val_u64(char *ptr, unsigned int offset)
>>  }
>>  
>>  /* Read headers of log records and dump accordingly */
>> -static void dump_dmesg_structured(int fd)
>> +void dump_dmesg_structured(int fd, handler_t handler)
>>  {
>>  #define OUT_BUF_SIZE	4096
>>  	uint64_t log_buf, log_buf_offset, ts_nsec;
>> @@ -733,7 +720,7 @@ static void dump_dmesg_structured(int fd)
>>  				out_buf[len++] = c;
>>  
>>  			if (len >= OUT_BUF_SIZE - 64) {
>> -				write_to_stdout(out_buf, len);
>> +				handler(out_buf, len);
>>  				len = 0;
>>  			}
>>  		}
>> @@ -753,25 +740,24 @@ static void dump_dmesg_structured(int fd)
>>  	}
>>  	free(buf);
>>  	if (len)
>> -		write_to_stdout(out_buf, len);
>> +		handler(out_buf, len);
>>  }
>>  
>> -static void dump_dmesg(int fd)
>> +int check_log_first_idx_vaddr(void)
>>  {
>>  	if (log_first_idx_vaddr)
>> -		dump_dmesg_structured(fd);
>> -	else
>> -		dump_dmesg_legacy(fd);
>> +		return 1;
>> +
>> +	return 0;
>>  }
>>  
>> -static int read_elf(int fd)
>> +int read_elf(int fd)
>>  {
>>  	int ret;
>>  
>>  	ret = pread(fd, ehdr.e_ident, EI_NIDENT, 0);
>>  	if (ret != EI_NIDENT) {
>> -		fprintf(stderr, "Read of e_ident from %s failed: %s\n",
>> -			fname, strerror(errno));
>> +		fprintf(stderr, "Read of e_ident failed: %s\n", strerror(errno));
>>  		return 3;
>>  	}
>>  	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) {
>> @@ -808,40 +794,13 @@ static int read_elf(int fd)
>>  	return 0;
>>  }
>>  
>> -int read_elf_vmcore(int fd)
>> -{
>> -	int ret;
>> -
>> -	ret = read_elf(fd);
>> -	if (ret > 0) {
>> -		fprintf(stderr, "Unable to read ELF information"
>> -			" from vmcore\n");
>> -		return ret;
>> -	}
>> -
>> -	dump_dmesg(fd);
>> -
>> -	return 0;
>> -}
>> -
>> -int read_elf_kcore(int fd)
>> -{
>> -	int ret;
>> -
>> -	ret = read_elf(fd);
>> -	if (ret != 0)
>> -		return ret;
>> -
>> -	return 0;
>> -}
> 
> I think that removing read_elf_kcore is not related to the rest of this
> patch and should be in a separate patch - it is a nice cleanup.
> 
Good idea, i will split them into a separate patch.

>> -
>>  int read_phys_offset_elf_kcore(int fd, unsigned long *phys_off)
>>  {
>>  	int ret;
>>  
>>  	*phys_off = UINT64_MAX;
>>  
>> -	ret = read_elf_kcore(fd);
>> +	ret = read_elf(fd);
>>  	if (!ret) {
>>  		/* If we have a valid 'PHYS_OFFSET' by now,
>>  		 * return it to the caller now.
>> diff --git a/util_lib/include/elf_info.h b/util_lib/include/elf_info.h
>> index 1a4debd2d4ba..8ee7d3e2763f 100644
>> --- a/util_lib/include/elf_info.h
>> +++ b/util_lib/include/elf_info.h
>> @@ -23,13 +23,17 @@
>>  #include <inttypes.h>
>>  #include <ctype.h>
>>  
>> +typedef void (*handler_t)(char *msg, unsigned int bytes);
> 
> I would prefer it if we did not add new typedefs.
> 

OK. I'm considering how to handle it. Any suggestions?

>> +
>>  int get_pt_load(int idx,
>>  	unsigned long long *phys_start,
>>  	unsigned long long *phys_end,
>>  	unsigned long long *virt_start,
>>  	unsigned long long *virt_end);
>>  int read_phys_offset_elf_kcore(int fd, unsigned long *phys_off);
>> -int read_elf_kcore(int fd);
>> -int read_elf_vmcore(int fd);
>> +int check_log_first_idx_vaddr(void);
>> +void dump_dmesg_structured(int fd, handler_t handler);
>> +void dump_dmesg_legacy(int fd, handler_t handler);
>> +int read_elf(int fd);
>>  
>>  #endif /* ELF_INFO_H */
>> diff --git a/vmcore-dmesg/vmcore-dmesg.c b/vmcore-dmesg/vmcore-dmesg.c
>> index 7a386b380291..ff0d540c9130 100644
>> --- a/vmcore-dmesg/vmcore-dmesg.c
>> +++ b/vmcore-dmesg/vmcore-dmesg.c
>> @@ -1,21 +1,53 @@
>>  #include <elf_info.h>
>>  
>> -/* The 32bit and 64bit note headers make it clear we don't care */
>> -typedef Elf32_Nhdr Elf_Nhdr;
>> +static void write_to_stdout(char *buf, unsigned int nr)
>> +{
>> +	ssize_t ret;
>> +
>> +	ret = write(STDOUT_FILENO, buf, nr);
>> +	if (ret != nr) {
>> +		fprintf(stderr, "Failed to write out the dmesg log buffer!:"
>> +				" %s\n", strerror(errno));
>> +		exit(54);
>> +	}
>> +}
>> +
>> +static void dump_dmesg(int fd, handler_t handler)
>> +{
>> +	if (check_log_first_idx_vaddr())
>> +		dump_dmesg_structured(fd, handler);
>> +	else
>> +		dump_dmesg_legacy(fd, handler);
>> +}
> 
> I think that dump_dmesg() could stay in kexec-arm64.c,
> it does not seem specific to vmcore handling.
> 

The dump_dmesg() should be a common function, not only arm64 will use it, but
x86 64 will also call it. It would be good to put the dump_dmesg() to a common
place.

>> -static const char *fname;
>> +static int read_vmcore_dmesg(int fd)
>> +{
>> +        int ret;
>> +
>> +        ret = read_elf(fd);
>> +        if (ret > 0) {
>> +                fprintf(stderr, "Unable to read ELF information"
>> +                        " from vmcore\n");
>> +                return ret;
>> +        }
>> +
>> +        dump_dmesg(fd, write_to_stdout);
>> +
>> +        return 0;
>> +}
>>  
>>  int main(int argc, char **argv)
>>  {
>>  	ssize_t ret;
>>  	int fd;
>> +	const char *fname;
>>  
>>  	if (argc != 2) {
>>  		fprintf(stderr, "usage: %s <kernel core file>\n", argv[0]);
>>  		return 1;
>>  	}
>> -	fname = argv[1];
>>  
>> +	fname = argv[1];
>>  	fd = open(fname, O_RDONLY);
>>  	if (fd < 0) {
>>  		fprintf(stderr, "Cannot open %s: %s\n",
>> @@ -23,8 +55,8 @@ int main(int argc, char **argv)
>>  		return 2;
>>  	}
>>  
>> -	ret = read_elf_vmcore(fd);
>> -	
>> +	ret = read_vmcore_dmesg(fd);
>> +
>>  	close(fd);
>>  
>>  	return ret;
>> -- 
>> 2.17.1
>>
>>
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>> kexec mailing list
>> kexec@lists.infradead.org
>> http://lists.infradead.org/mailman/listinfo/kexec
>>

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