linux/kernel/module.c, branch v5.7

Merge tag 'modules-for-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux

2020-04-09T19:52:34Z

Pull module updates from Jessica Yu: "Only a small cleanup this time around: a trivial conversion of zero-length arrays to flexible arrays" * tag 'modules-for-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux: kernel: module: Replace zero-length array with flexible-array member

proc: faster open/read/close with "permanent" files

2020-04-07T17:43:42Z

Now that "struct proc_ops" exist we can start putting there stuff which could not fly with VFS "struct file_operations"... Most of fs/proc/inode.c file is dedicated to make open/read/.../close reliable in the event of disappearing /proc entries which usually happens if module is getting removed. Files like /proc/cpuinfo which never disappear simply do not need such protection. Save 2 atomic ops, 1 allocation, 1 free per open/read/close sequence for such "permanent" files. Enable "permanent" flag for /proc/cpuinfo /proc/kmsg /proc/modules /proc/slabinfo /proc/stat /proc/sysvipc/* /proc/swaps More will come once I figure out foolproof way to prevent out module authors from marking their stuff "permanent" for performance reasons when it is not. This should help with scalability: benchmark is "read /proc/cpuinfo R times by N threads scattered over the system". N R t, s (before) t, s (after) ----------------------------------------------------- 64 4096 1.582458 1.530502 -3.2% 256 4096 6.371926 6.125168 -3.9% 1024 4096 25.64888 24.47528 -4.6% Benchmark source: #include #include #include #include #include #include #include #include const int NR_CPUS = sysconf(_SC_NPROCESSORS_ONLN); int N; const char *filename; int R; int xxx = 0; int glue(int n) { cpu_set_t m; CPU_ZERO(&m); CPU_SET(n, &m); return sched_setaffinity(0, sizeof(cpu_set_t), &m); } void f(int n) { glue(n % NR_CPUS); while (*(volatile int *)&xxx == 0) { } for (int i = 0; i < R; i++) { int fd = open(filename, O_RDONLY); char buf[4096]; ssize_t rv = read(fd, buf, sizeof(buf)); asm volatile ("" :: "g" (rv)); close(fd); } } int main(int argc, char *argv[]) { if (argc < 4) { std::cerr << "usage: " << argv[0] << ' ' << "N /proc/filename R "; return 1; } N = atoi(argv[1]); filename = argv[2]; R = atoi(argv[3]); for (int i = 0; i < NR_CPUS; i++) { if (glue(i) == 0) break; } std::vector T; T.reserve(N); for (int i = 0; i < N; i++) { T.emplace_back(f, i); } auto t0 = std::chrono::system_clock::now(); { *(volatile int *)&xxx = 1; for (auto& t: T) { t.join(); } } auto t1 = std::chrono::system_clock::now(); std::chrono::duration dt = t1 - t0; std::cout << dt.count() << ' '; return 0; } P.S.: Explicit randomization marker is added because adding non-function pointer will silently disable structure layout randomization. [akpm@linux-foundation.org: coding style fixes] Reported-by: kbuild test robot Reported-by: Dan Carpenter Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Cc: Al Viro Cc: Joe Perches Link: http://lkml.kernel.org/r/20200222201539.GA22576@avx2 Signed-off-by: Linus Torvalds

kernel: module: Replace zero-length array with flexible-array member

2020-02-17T20:40:55Z

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 Signed-off-by: Jessica Yu

proc: convert everything to "struct proc_ops"

2020-02-04T03:05:26Z

The most notable change is DEFINE_SHOW_ATTRIBUTE macro split in seq_file.h. Conversion rule is: llseek => proc_lseek unlocked_ioctl => proc_ioctl xxx => proc_xxx delete ".owner = THIS_MODULE" line [akpm@linux-foundation.org: fix drivers/isdn/capi/kcapi_proc.c] [sfr@canb.auug.org.au: fix kernel/sched/psi.c] Link: http://lkml.kernel.org/r/20200122180545.36222f50@canb.auug.org.au Link: http://lkml.kernel.org/r/20191225172546.GB13378@avx2 Signed-off-by: Alexey Dobriyan Signed-off-by: Stephen Rothwell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'modules-for-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux

2020-01-31T19:42:13Z

Pull module updates from Jessica Yu: "Summary of modules changes for the 5.6 merge window: - Add "MS" (SHF_MERGE|SHF_STRINGS) section flags to __ksymtab_strings to indicate to the linker that it can perform string deduplication (i.e., duplicate strings are reduced to a single copy in the string table). This means any repeated namespace string would be merged to just one entry in __ksymtab_strings. - Various code cleanups and small fixes (fix small memleak in error path, improve moduleparam docs, silence rcu warnings, improve error logging)" * tag 'modules-for-v5.6' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux: module.h: Annotate mod_kallsyms with __rcu module: avoid setting info->name early in case we can fall back to info->mod->name modsign: print module name along with error message kernel/module: Fix memleak in module_add_modinfo_attrs() export.h: reduce __ksymtab_strings string duplication by using "MS" section flags moduleparam: fix kerneldoc modules: lockdep: Suppress suspicious RCU usage warning

module: avoid setting info->name early in case we can fall back to info->mod->name

2020-01-20T15:59:39Z

In setup_load_info(), info->name (which contains the name of the module, mostly used for early logging purposes before the module gets set up) gets unconditionally assigned if .modinfo is missing despite the fact that there is an if (!info->name) check near the end of the function. Avoid assigning a placeholder string to info->name if .modinfo doesn't exist, so that we can fall back to info->mod->name later on. Fixes: 5fdc7db6448a ("module: setup load info before module_sig_check()") Reviewed-by: Miroslav Benes Signed-off-by: Jessica Yu

modsign: print module name along with error message

2020-01-15T14:49:31Z

It is useful to know which module failed signature verification, so print the module name along with the error message. Signed-off-by: Jessica Yu

kernel/module: Fix memleak in module_add_modinfo_attrs()

2020-01-08T16:07:20Z

In module_add_modinfo_attrs() if sysfs_create_file() fails on the first iteration of the loop (so i = 0), we forget to free the modinfo_attrs. Fixes: bc6f2a757d52 ("kernel/module: Fix mem leak in module_add_modinfo_attrs") Reviewed-by: Miroslav Benes Signed-off-by: YueHaibing Signed-off-by: Jessica Yu

Merge branch 'core/kprobes' into perf/core, to pick up a completed branch

2019-12-25T09:43:08Z

Signed-off-by: Ingo Molnar

Merge tag 'trace-v5.5-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

2019-12-11T20:22:38Z

Pull tracing fixes from Steven Rostedt: - Remove code I accidentally applied when doing a minor fix up to a patch, and then using "git commit -a --amend", which pulled in some other changes I was playing with. - Remove an used variable in trace_events_inject code - Fix function graph tracer when it traces a ftrace direct function. It will now ignore tracing a function that has a ftrace direct tramploine attached. This is needed for eBPF to use the ftrace direct code. * tag 'trace-v5.5-3' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: ftrace: Fix function_graph tracer interaction with BPF trampoline tracing: remove set but not used variable 'buffer' module: Remove accidental change of module_enable_x()