Commit fdbe123

zhuyifei1999 zhuyifei1999

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Unregister efrm-nondl on shutdown / reboot

On shutdown / reboot, if netdevs don't have a refcount of 1, the kernel loops with message: unregister_netdevice: waiting for eth0 to become free. Usage count = 3 unregister_netdevice: waiting for eth0 to become free. Usage count = 3 unregister_netdevice: waiting for eth0 to become free. Usage count = 3 [...] With netdev refcount tracking, the traces are visible: unregister_netdevice: waiting for eth0 to become free. Usage count = 3 ref_tracker: eth%d@ff3cf768c8344548 has 1/2 users at efrm_nic_add+0x29b/0x460 [sfc_resource] efrm_nondl_add_device+0x124/0x1c0 [sfc_resource] efrm_nondl_try_add_device+0x27/0xf0 [sfc_resource] efrm_nondl_register_netdev+0x106/0x160 [sfc_resource] nondl_register_store+0x174/0x1e0 [sfc_resource] kernfs_fop_write_iter+0x128/0x1c0 vfs_write+0x308/0x420 ksys_write+0x5f/0xe0 do_syscall_64+0x7b/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e ref_tracker: eth%d@ff3cf768c8344548 has 1/2 users at efrm_nondl_register_netdev+0xa9/0x160 [sfc_resource] nondl_register_store+0x174/0x1e0 [sfc_resource] kernfs_fop_write_iter+0x128/0x1c0 vfs_write+0x308/0x420 ksys_write+0x5f/0xe0 do_syscall_64+0x7b/0x160 entry_SYSCALL_64_after_hwframe+0x76/0x7e This patch makes sfc_resource register a reboot notifier that calls efrm_nondl_unregister & efrm_nondl_shutdown that handles each of the two refcounts. Considering that the only other caller of those functions is the cleanup_sfc_resource module exit function, I don't think shutdown should be concerned about module unload racing under normal circumstances. Signed-off-by: YiFei Zhu <zhuyifei@google.com>

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src/driver/linux_resource
- resource_driver.c

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+22

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`‎src/driver/linux_resource/resource_driver.c‎`

Lines changed: 22 additions & 0 deletions

Original file line number	Diff line number	Diff line change
`@@ -69,6 +69,7 @@`
`69`	`69`	`#include "sfcaffinity.h"`
`70`	`70`	`#include <ci/driver/resource/linux_efhw_nic.h>`
`71`	`71`	`#include <ci/driver/resource/driverlink.h>`
	`72`	`+#include <linux/reboot.h>`
`72`	`73`	`#include "debugfs.h"`
`73`	`74`
`74`	`75`	`MODULE_AUTHOR("Solarflare Communications");`
`@@ -631,6 +632,23 @@ static void efrm_nic_del_all(void)`
`631`	`632`	`efrm_nic_del(linux_efhw_nic(nic));`
`632`	`633`	`}`
`633`	`634`
	`635`	`+static void cleanup_sfc_resource(void);`
	`636`	`+`
	`637`	`+static int sfc_resource_shutdown_notify(struct notifier_block *unused1,`
	`638`	`+ unsigned long unused2, void *unused3)`
	`639`	`+{`
	`640`	`+ /* Due to refcounting reasons in netdev, these must`
	`641`	`+ * be called for the shutdown to happen without delays`
	`642`	`+ */`
	`643`	`+ efrm_nondl_unregister();`
	`644`	`+ efrm_nondl_shutdown();`
	`645`	`+`
	`646`	`+ return NOTIFY_DONE;`
	`647`	`+}`
	`648`	`+`
	`649`	`+static struct notifier_block sfc_resource_shutdown_nb = {`
	`650`	`+ .notifier_call = sfc_resource_shutdown_notify,`
	`651`	`+};`
`634`	`652`
`635`	`653`	`/****************************************************************************`
`636`	`654`	`*`
`@@ -683,6 +701,8 @@ static int init_sfc_resource(void)`
`683`	`701`	`efrm_install_sysfs_entries();`
`684`	`702`	`efrm_nondl_register();`
`685`	`703`
	`704`	`+ register_reboot_notifier(&sfc_resource_shutdown_nb);`
	`705`	`+`
`686`	`706`	`return 0;`
`687`	`707`
`688`	`708`	`failed_notifier:`
`@@ -705,6 +725,8 @@ static int init_sfc_resource(void)`
`705`	`725`	`****************************************************************************/`
`706`	`726`	`static void cleanup_sfc_resource(void)`
`707`	`727`	`{`
	`728`	`+ unregister_reboot_notifier(&sfc_resource_shutdown_nb);`
	`729`	`+`
`708`	`730`	`efrm_nondl_unregister();`
`709`	`731`	`efrm_remove_sysfs_entries();`
`710`	`732`	`efrm_nondl_shutdown();`

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`‎src/driver/linux_resource/resource_driver.c‎`

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