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From: Sascha Hauer <s.hauer@pengutronix.de>
To: Barebox List <barebox@lists.infradead.org>
Cc: "Daniel Glöckner" <dg@emlix.com>
Subject: [PATCH 18/19] fs: Warn when filesystem operations are called from a poller
Date: Wed, 17 Jun 2020 10:11:25 +0200	[thread overview]
Message-ID: <20200617081126.5683-19-s.hauer@pengutronix.de> (raw)
In-Reply-To: <20200617081126.5683-1-s.hauer@pengutronix.de>

Filesystem operations possibly call into arbitrary devices, so shouldn't
be used from a poller. This patch sprinkles some WARN_ONCE() when this
happens. One exception is when the file which is accessed is on ramfs
which doesn't have any dependencies to devices.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 common/poller.c |  2 +-
 fs/fs.c         | 35 +++++++++++++++++++++++++++++++++++
 include/slice.h |  6 ++++++
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/common/poller.c b/common/poller.c
index 7e8fb50122..d25fc9a294 100644
--- a/common/poller.c
+++ b/common/poller.c
@@ -16,7 +16,7 @@
 #include <slice.h>
 
 static LIST_HEAD(poller_list);
-static int poller_active;
+int poller_active;
 
 int poller_register(struct poller_struct *poller, const char *name)
 {
diff --git a/fs/fs.c b/fs/fs.c
index e04cadfe5d..d9bef0f852 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -31,6 +31,7 @@
 #include <environment.h>
 #include <libgen.h>
 #include <block.h>
+#include <slice.h>
 #include <libfile.h>
 #include <parseopt.h>
 #include <linux/namei.h>
@@ -74,6 +75,8 @@ static FILE *files;
 static struct dentry *d_root;
 static struct vfsmount *mnt_root;
 
+static struct fs_driver_d *ramfs_driver;
+
 static int init_fs(void)
 {
 	cwd = xzalloc(PATH_MAX);
@@ -250,6 +253,7 @@ static ssize_t __read(FILE *f, void *buf, size_t count)
 	struct fs_driver_d *fsdrv;
 	int ret;
 
+
 	if ((f->flags & O_ACCMODE) == O_WRONLY) {
 		ret = -EBADF;
 		goto out;
@@ -257,6 +261,9 @@ static ssize_t __read(FILE *f, void *buf, size_t count)
 
 	fsdrv = f->fsdev->driver;
 
+	if (fsdrv != ramfs_driver)
+		assert_command_context();
+
 	if (f->size != FILE_SIZE_STREAM && f->pos + count > f->size)
 		count = f->size - f->pos;
 
@@ -315,6 +322,10 @@ static ssize_t __write(FILE *f, const void *buf, size_t count)
 	}
 
 	fsdrv = f->fsdev->driver;
+
+	if (fsdrv != ramfs_driver)
+		assert_command_context();
+
 	if (f->size != FILE_SIZE_STREAM && f->pos + count > f->size) {
 		ret = fsdrv->truncate(&f->fsdev->dev, f, f->pos + count);
 		if (ret) {
@@ -402,6 +413,9 @@ loff_t lseek(int fd, loff_t offset, int whence)
 
 	fsdrv = f->fsdev->driver;
 
+	if (fsdrv != ramfs_driver)
+		assert_command_context();
+
 	ret = -EINVAL;
 
 	switch (whence) {
@@ -457,6 +471,10 @@ int erase(int fd, loff_t count, loff_t offset)
 		return -EINVAL;
 
 	fsdrv = f->fsdev->driver;
+
+	if (fsdrv != ramfs_driver)
+		assert_command_context();
+
 	if (fsdrv->erase)
 		ret = fsdrv->erase(&f->fsdev->dev, f, count, offset);
 	else
@@ -483,6 +501,10 @@ int protect(int fd, size_t count, loff_t offset, int prot)
 		count = f->size - offset;
 
 	fsdrv = f->fsdev->driver;
+
+	if (fsdrv != ramfs_driver)
+		assert_command_context();
+
 	if (fsdrv->protect)
 		ret = fsdrv->protect(&f->fsdev->dev, f, count, offset, prot);
 	else
@@ -509,6 +531,10 @@ int discard_range(int fd, loff_t count, loff_t offset)
 		count = f->size - offset;
 
 	fsdrv = f->fsdev->driver;
+
+	if (fsdrv != ramfs_driver)
+		assert_command_context();
+
 	if (fsdrv->discard_range)
 		ret = fsdrv->discard_range(&f->fsdev->dev, f, count, offset);
 	else
@@ -547,6 +573,9 @@ void *memmap(int fd, int flags)
 
 	fsdrv = f->fsdev->driver;
 
+	if (fsdrv != ramfs_driver)
+		assert_command_context();
+
 	if (fsdrv->memmap)
 		ret = fsdrv->memmap(&f->fsdev->dev, f, &retp, flags);
 	else
@@ -570,6 +599,9 @@ int close(int fd)
 
 	fsdrv = f->fsdev->driver;
 
+	if (fsdrv != ramfs_driver)
+		assert_command_context();
+
 	if (fsdrv->close)
 		ret = fsdrv->close(&f->fsdev->dev, f);
 
@@ -700,6 +732,9 @@ int register_fs_driver(struct fs_driver_d *fsdrv)
 	fsdrv->drv.bus = &fs_bus;
 	register_driver(&fsdrv->drv);
 
+	if (!strcmp(fsdrv->drv.name, "ramfs"))
+		ramfs_driver = fsdrv;
+
 	return 0;
 }
 EXPORT_SYMBOL(register_fs_driver);
diff --git a/include/slice.h b/include/slice.h
index fd753e194b..5438aeef90 100644
--- a/include/slice.h
+++ b/include/slice.h
@@ -33,4 +33,10 @@ extern struct slice command_slice;
 void command_slice_acquire(void);
 void command_slice_release(void);
 
+extern int poller_active;
+
+#define assert_command_context() ({    \
+	WARN_ONCE(poller_active, "%s called in poller\n", __func__); \
+})
+
 #endif /* __SLICE_H */
-- 
2.27.0


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  parent reply	other threads:[~2020-06-17  8:11 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-17  8:11 [PATCH v4 00/19] Slices and fastboot over UDP Sascha Hauer
2020-06-17  8:11 ` [PATCH 01/19] Introduce slices Sascha Hauer
2020-06-17  8:11 ` [PATCH 02/19] Add workqueues Sascha Hauer
2020-06-17 18:30   ` Daniel Glöckner
2020-06-17 19:56     ` Sascha Hauer
2020-06-17  8:11 ` [PATCH 03/19] ratp: Switch to workqueues Sascha Hauer
2020-06-17  8:11 ` [PATCH 04/19] net: Add a slice to struct eth_device Sascha Hauer
2020-06-17  8:11 ` [PATCH 05/19] net: mdiobus: Add slice Sascha Hauer
2020-06-17  8:11 ` [PATCH 06/19] usb: Add a slice to usb host controllers Sascha Hauer
2020-06-17  8:11 ` [PATCH 07/19] usbnet: Add slice Sascha Hauer
2020-06-17  8:11 ` [PATCH 08/19] net: Call net_poll() in a poller Sascha Hauer
2020-06-17  8:11 ` [PATCH 09/19] net: reply to ping requests Sascha Hauer
2020-06-17  8:11 ` [PATCH 10/19] usbnet: Be more friendly in the receive path Sascha Hauer
2020-06-17  8:11 ` [PATCH 11/19] defconfigs: update renamed fastboot options Sascha Hauer
2020-06-17  8:11 ` [PATCH 12/19] globalvar: Add helper for deprecated variable names Sascha Hauer
2020-06-17  8:11 ` [PATCH 13/19] fastboot: rename usbgadget.fastboot_* variables to fastboot.* Sascha Hauer
2020-06-17  8:11 ` [PATCH 14/19] fastboot: remove double print Sascha Hauer
2020-06-17 18:24   ` Daniel Glöckner
2020-06-17 19:54     ` Sascha Hauer
2020-06-18 19:08       ` Daniel Glöckner
2020-06-19  7:01         ` Sascha Hauer
2020-06-17  8:11 ` [PATCH 15/19] fastboot net: implement fastboot over UDP Sascha Hauer
2020-06-17 19:32   ` Daniel Glöckner
2020-06-18 11:59     ` Sascha Hauer
2020-06-18 18:33       ` Daniel Glöckner
2020-06-19  7:38         ` Sascha Hauer
2020-06-17  8:11 ` [PATCH 16/19] usb: fastboot: execute commands in command context Sascha Hauer
2020-06-17 19:40   ` Daniel Glöckner
2020-06-18  7:26     ` Sascha Hauer
2020-06-17  8:11 ` [PATCH 17/19] Add WARN_ONCE() macro Sascha Hauer
2020-06-17  8:11 ` Sascha Hauer [this message]
2020-06-17  8:11 ` [PATCH 19/19] Documentation: Add document for parallel execution in barebox Sascha Hauer

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