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33c9da5dfb
The existing sigio workaround implementation removes FDs from the poll when events are triggered, requiring users to re-add them via add_sigio_fd() after processing. This introduces a potential race condition between FD removal in write_sigio_thread() and next_poll update in __add_sigio_fd(), and is inefficient due to frequent FD removal and re-addition. Rewrite the implementation based on epoll and tgkill for improved efficiency and reliability. Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com> Link: https://patch.msgid.link/20250315161910.4082396-2-tiwei.btw@antgroup.com Signed-off-by: Johannes Berg <johannes.berg@intel.com>
121 lines
2.5 KiB
C
121 lines
2.5 KiB
C
/* Copyright (C) 2005 - 2008 Jeff Dike <jdike@{linux.intel,addtoit}.com> */
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/* Much of this ripped from drivers/char/hw_random.c, see there for other
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* copyright.
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*
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* This software may be used and distributed according to the terms
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* of the GNU General Public License, incorporated herein by reference.
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*/
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#include <linux/sched/signal.h>
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#include <linux/module.h>
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#include <linux/fs.h>
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#include <linux/interrupt.h>
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#include <linux/miscdevice.h>
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#include <linux/hw_random.h>
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#include <linux/delay.h>
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#include <linux/uaccess.h>
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#include <init.h>
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#include <irq_kern.h>
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#include <os.h>
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/*
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* core module information
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*/
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#define RNG_MODULE_NAME "hw_random"
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/* Changed at init time, in the non-modular case, and at module load
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* time, in the module case. Presumably, the module subsystem
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* protects against a module being loaded twice at the same time.
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*/
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static int random_fd = -1;
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static struct hwrng hwrng;
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static DECLARE_COMPLETION(have_data);
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static int rng_dev_read(struct hwrng *rng, void *buf, size_t max, bool block)
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{
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int ret;
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for (;;) {
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ret = os_read_file(random_fd, buf, max);
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if (block && ret == -EAGAIN) {
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add_sigio_fd(random_fd);
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ret = wait_for_completion_killable(&have_data);
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ignore_sigio_fd(random_fd);
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deactivate_fd(random_fd, RANDOM_IRQ);
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if (ret < 0)
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break;
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} else {
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break;
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}
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}
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return ret != -EAGAIN ? ret : 0;
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}
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static irqreturn_t random_interrupt(int irq, void *data)
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{
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complete(&have_data);
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return IRQ_HANDLED;
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}
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/*
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* rng_init - initialize RNG module
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*/
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static int __init rng_init (void)
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{
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int err;
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err = os_open_file("/dev/random", of_read(OPENFLAGS()), 0);
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if (err < 0)
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goto out;
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random_fd = err;
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err = um_request_irq(RANDOM_IRQ, random_fd, IRQ_READ, random_interrupt,
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0, "random", NULL);
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if (err < 0)
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goto err_out_cleanup_hw;
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sigio_broken();
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hwrng.name = RNG_MODULE_NAME;
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hwrng.read = rng_dev_read;
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err = hwrng_register(&hwrng);
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if (err) {
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pr_err(RNG_MODULE_NAME " registering failed (%d)\n", err);
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goto err_out_cleanup_hw;
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}
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out:
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return err;
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err_out_cleanup_hw:
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os_close_file(random_fd);
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random_fd = -1;
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goto out;
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}
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/*
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* rng_cleanup - shutdown RNG module
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*/
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static void cleanup(void)
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{
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free_irq_by_fd(random_fd);
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os_close_file(random_fd);
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}
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static void __exit rng_cleanup(void)
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{
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hwrng_unregister(&hwrng);
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os_close_file(random_fd);
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}
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module_init (rng_init);
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module_exit (rng_cleanup);
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__uml_exitcall(cleanup);
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MODULE_DESCRIPTION("UML Host Random Number Generator (RNG) driver");
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MODULE_LICENSE("GPL");
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