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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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053c095a82
Contrary to common expectations for an "int" return, these functions return only a positive value -- if used correctly they cannot even return 0 because the message header will necessarily be in the skb. This makes the very common pattern of if (genlmsg_end(...) < 0) { ... } be a whole bunch of dead code. Many places also simply do return nlmsg_end(...); and the caller is expected to deal with it. This also commonly (at least for me) causes errors, because it is very common to write if (my_function(...)) /* error condition */ and if my_function() does "return nlmsg_end()" this is of course wrong. Additionally, there's not a single place in the kernel that actually needs the message length returned, and if anyone needs it later then it'll be very easy to just use skb->len there. Remove this, and make the functions void. This removes a bunch of dead code as described above. The patch adds lines because I did - return nlmsg_end(...); + nlmsg_end(...); + return 0; I could have preserved all the function's return values by returning skb->len, but instead I've audited all the places calling the affected functions and found that none cared. A few places actually compared the return value with <= 0 in dump functionality, but that could just be changed to < 0 with no change in behaviour, so I opted for the more efficient version. One instance of the error I've made numerous times now is also present in net/phonet/pn_netlink.c in the route_dumpit() function - it didn't check for <0 or <=0 and thus broke out of the loop every single time. I've preserved this since it will (I think) have caused the messages to userspace to be formatted differently with just a single message for every SKB returned to userspace. It's possible that this isn't needed for the tools that actually use this, but I don't even know what they are so couldn't test that changing this behaviour would be acceptable. Signed-off-by: Johannes Berg <johannes.berg@intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
184 lines
4.2 KiB
C
184 lines
4.2 KiB
C
/*
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* event.c - exporting ACPI events via procfs
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*
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* Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
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* Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
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*
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*/
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#include <linux/spinlock.h>
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#include <linux/export.h>
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#include <linux/proc_fs.h>
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#include <linux/init.h>
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#include <linux/poll.h>
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#include <linux/gfp.h>
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#include <linux/acpi.h>
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#include <net/netlink.h>
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#include <net/genetlink.h>
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#include "internal.h"
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#define _COMPONENT ACPI_SYSTEM_COMPONENT
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ACPI_MODULE_NAME("event");
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/* ACPI notifier chain */
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static BLOCKING_NOTIFIER_HEAD(acpi_chain_head);
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int acpi_notifier_call_chain(struct acpi_device *dev, u32 type, u32 data)
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{
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struct acpi_bus_event event;
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strcpy(event.device_class, dev->pnp.device_class);
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strcpy(event.bus_id, dev->pnp.bus_id);
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event.type = type;
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event.data = data;
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return (blocking_notifier_call_chain(&acpi_chain_head, 0, (void *)&event)
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== NOTIFY_BAD) ? -EINVAL : 0;
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}
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EXPORT_SYMBOL(acpi_notifier_call_chain);
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int register_acpi_notifier(struct notifier_block *nb)
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{
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return blocking_notifier_chain_register(&acpi_chain_head, nb);
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}
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EXPORT_SYMBOL(register_acpi_notifier);
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int unregister_acpi_notifier(struct notifier_block *nb)
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{
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return blocking_notifier_chain_unregister(&acpi_chain_head, nb);
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}
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EXPORT_SYMBOL(unregister_acpi_notifier);
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#ifdef CONFIG_NET
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static unsigned int acpi_event_seqnum;
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struct acpi_genl_event {
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acpi_device_class device_class;
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char bus_id[15];
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u32 type;
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u32 data;
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};
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/* attributes of acpi_genl_family */
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enum {
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ACPI_GENL_ATTR_UNSPEC,
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ACPI_GENL_ATTR_EVENT, /* ACPI event info needed by user space */
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__ACPI_GENL_ATTR_MAX,
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};
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#define ACPI_GENL_ATTR_MAX (__ACPI_GENL_ATTR_MAX - 1)
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/* commands supported by the acpi_genl_family */
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enum {
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ACPI_GENL_CMD_UNSPEC,
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ACPI_GENL_CMD_EVENT, /* kernel->user notifications for ACPI events */
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__ACPI_GENL_CMD_MAX,
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};
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#define ACPI_GENL_CMD_MAX (__ACPI_GENL_CMD_MAX - 1)
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#define ACPI_GENL_FAMILY_NAME "acpi_event"
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#define ACPI_GENL_VERSION 0x01
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#define ACPI_GENL_MCAST_GROUP_NAME "acpi_mc_group"
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static const struct genl_multicast_group acpi_event_mcgrps[] = {
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{ .name = ACPI_GENL_MCAST_GROUP_NAME, },
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};
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static struct genl_family acpi_event_genl_family = {
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.id = GENL_ID_GENERATE,
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.name = ACPI_GENL_FAMILY_NAME,
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.version = ACPI_GENL_VERSION,
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.maxattr = ACPI_GENL_ATTR_MAX,
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.mcgrps = acpi_event_mcgrps,
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.n_mcgrps = ARRAY_SIZE(acpi_event_mcgrps),
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};
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int acpi_bus_generate_netlink_event(const char *device_class,
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const char *bus_id,
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u8 type, int data)
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{
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struct sk_buff *skb;
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struct nlattr *attr;
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struct acpi_genl_event *event;
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void *msg_header;
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int size;
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/* allocate memory */
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size = nla_total_size(sizeof(struct acpi_genl_event)) +
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nla_total_size(0);
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skb = genlmsg_new(size, GFP_ATOMIC);
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if (!skb)
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return -ENOMEM;
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/* add the genetlink message header */
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msg_header = genlmsg_put(skb, 0, acpi_event_seqnum++,
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&acpi_event_genl_family, 0,
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ACPI_GENL_CMD_EVENT);
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if (!msg_header) {
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nlmsg_free(skb);
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return -ENOMEM;
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}
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/* fill the data */
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attr =
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nla_reserve(skb, ACPI_GENL_ATTR_EVENT,
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sizeof(struct acpi_genl_event));
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if (!attr) {
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nlmsg_free(skb);
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return -EINVAL;
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}
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event = nla_data(attr);
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memset(event, 0, sizeof(struct acpi_genl_event));
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strcpy(event->device_class, device_class);
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strcpy(event->bus_id, bus_id);
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event->type = type;
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event->data = data;
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/* send multicast genetlink message */
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genlmsg_end(skb, msg_header);
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genlmsg_multicast(&acpi_event_genl_family, skb, 0, 0, GFP_ATOMIC);
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return 0;
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}
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EXPORT_SYMBOL(acpi_bus_generate_netlink_event);
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static int acpi_event_genetlink_init(void)
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{
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return genl_register_family(&acpi_event_genl_family);
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}
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#else
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int acpi_bus_generate_netlink_event(const char *device_class,
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const char *bus_id,
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u8 type, int data)
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{
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return 0;
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}
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EXPORT_SYMBOL(acpi_bus_generate_netlink_event);
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static int acpi_event_genetlink_init(void)
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{
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return -ENODEV;
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}
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#endif
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static int __init acpi_event_init(void)
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{
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int error = 0;
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if (acpi_disabled)
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return 0;
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/* create genetlink for acpi event */
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error = acpi_event_genetlink_init();
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if (error)
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printk(KERN_WARNING PREFIX
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"Failed to create genetlink family for ACPI event\n");
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return 0;
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}
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fs_initcall(acpi_event_init);
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