mirror of
https://github.com/dynup/kpatch
synced 2025-01-09 14:49:28 +00:00
kmod: error handling cleanup
Cleanup the error handling a little bit and make the flow a little clearer.
This commit is contained in:
Josh Poimboeuf
parent
892c630ce3
commit
ff28767295
@ -172,6 +172,7 @@ static int kpatch_apply_patch(void *data)
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/* update the global list and go live */
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hash_add_rcu(kpatch_func_hash, &func->node, func->old_addr);
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}
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/* Check if any inconsistent NMI has happened while updating */
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ret = kpatch_finish_status(KPATCH_STATUS_SUCCESS);
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if (ret == KPATCH_STATUS_FAILURE) {
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@ -179,12 +180,13 @@ static int kpatch_apply_patch(void *data)
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for (i = 0; i < num_funcs; i++)
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hash_del_rcu(&funcs[i].node);
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ret = -EBUSY;
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} else {
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/* Succeeded, clear updating flags */
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for (i = 0; i < num_funcs; i++)
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funcs[i].updating = false;
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ret = 0;
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goto out;
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}
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ret = 0;
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/* Succeeded, clear updating flags */
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for (i = 0; i < num_funcs; i++)
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funcs[i].updating = false;
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out:
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return ret;
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}
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@ -208,12 +210,13 @@ static int kpatch_remove_patch(void *data)
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for (i = 0; i < num_funcs; i++)
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funcs[i].updating = false;
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ret = -EBUSY;
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} else {
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/* Succeeded, remove all updating funcs from hash table */
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for (i = 0; i < num_funcs; i++)
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hash_del_rcu(&funcs[i].node);
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ret = 0;
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goto out;
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}
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/* Succeeded, remove all updating funcs from hash table */
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for (i = 0; i < num_funcs; i++)
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hash_del_rcu(&funcs[i].node);
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ret = 0;
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out:
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return ret;
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}
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@ -241,6 +244,14 @@ static struct kpatch_func *kpatch_get_committed_func(struct kpatch_func *f,
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return NULL;
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}
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/*
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* This is where the magic happens. Update regs->ip to tell ftrace to return
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* to the new function.
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*
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* If there are multiple patch modules that have registered to patch the same
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* function, the last one to register wins, as it'll be first in the hash
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* bucket.
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*/
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void notrace kpatch_ftrace_handler(unsigned long ip, unsigned long parent_ip,
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struct ftrace_ops *fops,
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struct pt_regs *regs)
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@ -248,14 +259,6 @@ void notrace kpatch_ftrace_handler(unsigned long ip, unsigned long parent_ip,
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struct kpatch_func *func;
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int ret, op;
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/*
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* This is where the magic happens. Update regs->ip to tell ftrace to
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* return to the new function.
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*
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* If there are multiple patch modules that have registered to patch
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* the same function, the last one to register wins, as it'll be first
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* in the hash bucket.
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*/
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preempt_disable_notrace();
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retry:
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func = kpatch_get_func(ip);
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@ -343,7 +346,7 @@ static int kpatch_remove_funcs_from_filter(struct kpatch_func *funcs,
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int kpatch_register(struct module *mod, struct kpatch_func *funcs,
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int num_funcs)
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{
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int ret, ret2, i;
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int ret, i;
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struct kpatch_stop_machine_args args = {
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.funcs = funcs,
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.num_funcs = num_funcs,
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@ -371,20 +374,19 @@ int kpatch_register(struct module *mod, struct kpatch_func *funcs,
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pr_err("can't set ftrace filter at address 0x%lx\n",
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func->old_addr);
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num_funcs = i;
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goto out;
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goto err_rollback;
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}
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}
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/* Register the ftrace trampoline if it hasn't been done already. */
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if (!kpatch_num_registered++) {
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if (!kpatch_num_registered) {
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ret = register_ftrace_function(&kpatch_ftrace_ops);
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if (ret) {
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pr_err("can't register ftrace handler\n");
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/* For the next time, the counter should be unrolled */
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--kpatch_num_registered;
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goto out;
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goto err_rollback;
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}
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}
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kpatch_num_registered++;
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kpatch_start_status();
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/*
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@ -399,35 +401,38 @@ int kpatch_register(struct module *mod, struct kpatch_func *funcs,
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*/
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ret = stop_machine(kpatch_apply_patch, &args, NULL);
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if (ret) {
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if (!--kpatch_num_registered) {
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ret2 = unregister_ftrace_function(&kpatch_ftrace_ops);
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if (ret2)
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pr_err("ftrace unregister failed (%d)\n", ret2);
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}
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/*
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* This synchronize_rcu is to ensure any other kpatch_get_func
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* user exits the rcu locked(preemt_disabled) critical section
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* and hash_del_rcu() is correctly finished.
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*/
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synchronize_rcu();
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goto err_unregister;
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}
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/* TODO: need TAINT_KPATCH */
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pr_notice_once("tainting kernel with TAINT_USER\n");
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add_taint(TAINT_USER, LOCKDEP_STILL_OK);
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pr_notice("loaded patch module \"%s\"\n", mod->name);
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out:
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/* Rollback the filter if we get any error */
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if (ret)
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kpatch_remove_funcs_from_filter(funcs, num_funcs);
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else {
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/* TODO: need TAINT_KPATCH */
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pr_notice_once("tainting kernel with TAINT_USER\n");
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add_taint(TAINT_USER, LOCKDEP_STILL_OK);
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pr_notice("loaded patch module \"%s\"\n", mod->name);
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}
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atomic_set(&kpatch_operation, KPATCH_OP_NONE);
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up(&kpatch_mutex);
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return ret;
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err_unregister:
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if (kpatch_num_registered == 1) {
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int ret2 = unregister_ftrace_function(&kpatch_ftrace_ops);
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if (ret2) {
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pr_err("ftrace unregister failed (%d)\n", ret2);
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goto err_rollback;
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}
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}
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kpatch_num_registered--;
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err_rollback:
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kpatch_remove_funcs_from_filter(funcs, num_funcs);
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goto out;
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}
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EXPORT_SYMBOL(kpatch_register);
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@ -457,13 +462,15 @@ int kpatch_unregister(struct module *mod, struct kpatch_func *funcs,
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if (ret)
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goto out;
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if (!--kpatch_num_registered) {
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if (kpatch_num_registered == 1) {
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ret = unregister_ftrace_function(&kpatch_ftrace_ops);
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if (ret) {
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pr_err("can't unregister ftrace handler\n");
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goto out;
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}
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}
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kpatch_num_registered--;
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/*
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* This synchronize_rcu is to ensure any other kpatch_get_func
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* user exits the rcu locked(preemt_disabled) critical section
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@ -472,8 +479,10 @@ int kpatch_unregister(struct module *mod, struct kpatch_func *funcs,
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synchronize_rcu();
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ret = kpatch_remove_funcs_from_filter(funcs, num_funcs);
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if (ret == 0)
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pr_notice("unloaded patch module \"%s\"\n", mod->name);
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if (ret)
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goto out;
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pr_notice("unloaded patch module \"%s\"\n", mod->name);
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out:
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atomic_set(&kpatch_operation, KPATCH_OP_NONE);
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@ -33,7 +33,7 @@ static int num_funcs;
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static int __init patch_init(void)
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{
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struct kpatch_patch *patches;
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int i;
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int i, ret;
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patches = (struct kpatch_patch *)&__kpatch_patches;
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num_funcs = (&__kpatch_patches_end - &__kpatch_patches) /
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@ -48,7 +48,15 @@ static int __init patch_init(void)
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funcs[i].new_addr = patches[i].new_addr;
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}
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return kpatch_register(THIS_MODULE, funcs, num_funcs);
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ret = kpatch_register(THIS_MODULE, funcs, num_funcs);
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if (ret)
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goto err_free;
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return 0;
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err_free:
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kfree(funcs);
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return ret;
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}
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static void __exit patch_exit(void)
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