a0e026e7b3
Since commit 91a7cda1f4b8 ("net: phy: Fix race condition on link status
change") all the phy_error() method invocations have been causing the
nested-mutex-lock deadlock because it's normally done in the PHY-driver
threaded IRQ handlers which since that change have been called with the
phydev->lock mutex held. Here is the calls thread:
IRQ: phy_interrupt()
+-> mutex_lock(&phydev->lock); <--------------------+
drv->handle_interrupt() | Deadlock due
+-> ERROR: phy_error() + to the nested
+-> phy_process_error() | mutex lock
+-> mutex_lock(&phydev->lock); <-+
phydev->state = PHY_ERROR;
mutex_unlock(&phydev->lock);
mutex_unlock(&phydev->lock);
The problem can be easily reproduced just by calling phy_error() from any
PHY-device threaded interrupt handler. Fix it by dropping the phydev->lock
mutex lock from the phy_process_error() method and printing a nasty error
message to the system log if the mutex isn't held in the caller execution
context.
Note for the fix to work correctly in the PHY-subsystem itself the
phydev->lock mutex locking must be added to the phy_error_precise()
function.
Link: https://lore.kernel.org/netdev/20230816180944.19262-1-fancer.lancer@gmail.com
Fixes: 91a7cda1f4b8 ("net: phy: Fix race condition on link status change")
Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.