From: Alexey Dobriyan <adobriyan@xxxxxxxxx> Subject: proc: less code duplication in /proc/*/cmdline After staring at this code for a while I've figured using small 2-entry array describing ARGV and ENVP is the way to address code duplication critique. Link: http://lkml.kernel.org/r/20170105185724.GA12027@avx2 Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/base.c | 142 ++++++++++++++++++----------------------------- 1 file changed, 55 insertions(+), 87 deletions(-) diff -puN fs/proc/base.c~proc-less-code-duplication-in-proc-cmdline fs/proc/base.c --- a/fs/proc/base.c~proc-less-code-duplication-in-proc-cmdline +++ a/fs/proc/base.c @@ -292,101 +292,69 @@ static ssize_t proc_pid_cmdline_read(str } } else { /* - * Command line (1 string) occupies ARGV and maybe - * extends into ENVP. - */ - if (len1 + len2 <= *pos) - goto skip_argv_envp; - if (len1 <= *pos) - goto skip_argv; - - p = arg_start + *pos; - len = len1 - *pos; - while (count > 0 && len > 0) { - unsigned int _count, l; - int nr_read; - bool final; - - _count = min3(count, len, PAGE_SIZE); - nr_read = access_remote_vm(mm, p, page, _count, 0); - if (nr_read < 0) - rv = nr_read; - if (nr_read <= 0) - goto out_free_page; - - /* - * Command line can be shorter than whole ARGV - * even if last "marker" byte says it is not. - */ - final = false; - l = strnlen(page, nr_read); - if (l < nr_read) { - nr_read = l; - final = true; - } - - if (copy_to_user(buf, page, nr_read)) { - rv = -EFAULT; - goto out_free_page; - } - - p += nr_read; - len -= nr_read; - buf += nr_read; - count -= nr_read; - rv += nr_read; - - if (final) - goto out_free_page; - } -skip_argv: - /* * Command line (1 string) occupies ARGV and * extends into ENVP. */ - if (len1 <= *pos) { - p = env_start + *pos - len1; - len = len1 + len2 - *pos; - } else { - p = env_start; - len = len2; + struct { + unsigned long p; + unsigned long len; + } cmdline[2] = { + { .p = arg_start, .len = len1 }, + { .p = env_start, .len = len2 }, + }; + loff_t pos1 = *pos; + unsigned int i; + + i = 0; + while (i < 2 && pos1 >= cmdline[i].len) { + pos1 -= cmdline[i].len; + i++; } - while (count > 0 && len > 0) { - unsigned int _count, l; - int nr_read; - bool final; - - _count = min3(count, len, PAGE_SIZE); - nr_read = access_remote_vm(mm, p, page, _count, 0); - if (nr_read < 0) - rv = nr_read; - if (nr_read <= 0) - goto out_free_page; - - /* Find EOS. */ - final = false; - l = strnlen(page, nr_read); - if (l < nr_read) { - nr_read = l; - final = true; - } + while (i < 2) { + p = cmdline[i].p + pos1; + len = cmdline[i].len - pos1; + while (count > 0 && len > 0) { + unsigned int _count, l; + int nr_read; + bool final; + + _count = min3(count, len, PAGE_SIZE); + nr_read = access_remote_vm(mm, p, page, _count, 0); + if (nr_read < 0) + rv = nr_read; + if (nr_read <= 0) + goto out_free_page; + + /* + * Command line can be shorter than whole ARGV + * even if last "marker" byte says it is not. + */ + final = false; + l = strnlen(page, nr_read); + if (l < nr_read) { + nr_read = l; + final = true; + } + + if (copy_to_user(buf, page, nr_read)) { + rv = -EFAULT; + goto out_free_page; + } + + p += nr_read; + len -= nr_read; + buf += nr_read; + count -= nr_read; + rv += nr_read; - if (copy_to_user(buf, page, nr_read)) { - rv = -EFAULT; - goto out_free_page; + if (final) + goto out_free_page; } - p += nr_read; - len -= nr_read; - buf += nr_read; - count -= nr_read; - rv += nr_read; - - if (final) - goto out_free_page; + /* Only first chunk can be read partially. */ + pos1 = 0; + i++; } -skip_argv_envp: - ; } out_free_page: _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
