Revision 3dbae15538972c9e1578cb216964c2840361a538 authored by Gustavo A. R. Silva on 15 February 2020, 01:03:12 UTC, committed by Dmitry Torokhov on 15 February 2020, 01:19:22 UTC
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com> Link: https://lore.kernel.org/r/20200214172132.GA28389@embeddedor Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
1 parent 94bef5d
bloat-o-meter
#!/usr/bin/python
#
# Copyright 2004 Matt Mackall <mpm@selenic.com>
#
# inspired by perl Bloat-O-Meter (c) 1997 by Andi Kleen
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.
import sys, os, re
from signal import signal, SIGPIPE, SIG_DFL
signal(SIGPIPE, SIG_DFL)
if len(sys.argv) < 3:
sys.stderr.write("usage: %s [option] file1 file2\n" % sys.argv[0])
sys.stderr.write("The options are:\n")
sys.stderr.write("-c categorize output based on symbol type\n")
sys.stderr.write("-d Show delta of Data Section\n")
sys.stderr.write("-t Show delta of text Section\n")
sys.exit(-1)
re_NUMBER = re.compile(r'\.[0-9]+')
def getsizes(file, format):
sym = {}
with os.popen("nm --size-sort " + file) as f:
for line in f:
size, type, name = line.split()
if type in format:
# strip generated symbols
if name.startswith("__mod_"): continue
if name.startswith("__se_sys"): continue
if name.startswith("__se_compat_sys"): continue
if name.startswith("__addressable_"): continue
if name == "linux_banner": continue
# statics and some other optimizations adds random .NUMBER
name = re_NUMBER.sub('', name)
sym[name] = sym.get(name, 0) + int(size, 16)
return sym
def calc(oldfile, newfile, format):
old = getsizes(oldfile, format)
new = getsizes(newfile, format)
grow, shrink, add, remove, up, down = 0, 0, 0, 0, 0, 0
delta, common = [], {}
otot, ntot = 0, 0
for a in old:
if a in new:
common[a] = 1
for name in old:
otot += old[name]
if name not in common:
remove += 1
down += old[name]
delta.append((-old[name], name))
for name in new:
ntot += new[name]
if name not in common:
add += 1
up += new[name]
delta.append((new[name], name))
for name in common:
d = new.get(name, 0) - old.get(name, 0)
if d>0: grow, up = grow+1, up+d
if d<0: shrink, down = shrink+1, down-d
delta.append((d, name))
delta.sort()
delta.reverse()
return grow, shrink, add, remove, up, down, delta, old, new, otot, ntot
def print_result(symboltype, symbolformat, argc):
grow, shrink, add, remove, up, down, delta, old, new, otot, ntot = \
calc(sys.argv[argc - 1], sys.argv[argc], symbolformat)
print("add/remove: %s/%s grow/shrink: %s/%s up/down: %s/%s (%s)" % \
(add, remove, grow, shrink, up, -down, up-down))
print("%-40s %7s %7s %+7s" % (symboltype, "old", "new", "delta"))
for d, n in delta:
if d: print("%-40s %7s %7s %+7d" % (n, old.get(n,"-"), new.get(n,"-"), d))
if otot:
percent = (ntot - otot) * 100.0 / otot
else:
percent = 0
print("Total: Before=%d, After=%d, chg %+.2f%%" % (otot, ntot, percent))
if sys.argv[1] == "-c":
print_result("Function", "tT", 3)
print_result("Data", "dDbB", 3)
print_result("RO Data", "rR", 3)
elif sys.argv[1] == "-d":
print_result("Data", "dDbBrR", 3)
elif sys.argv[1] == "-t":
print_result("Function", "tT", 3)
else:
print_result("Function", "tTdDbBrR", 2)
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