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__netdev_alloc_skb() can be used from any context and is used by NAPI and non-NAPI drivers. Non-NAPI drivers use it in interrupt context and NAPI drivers use it during initial allocation (->ndo_open() or ->ndo_change_mtu()). Some NAPI drivers share the same function for the initial allocation and the allocation in their NAPI callback. The interrupts are disabled in order to ensure locked access from every context to `netdev_alloc_cache'. Let __netdev_alloc_skb() check if interrupts are disabled. If they are, use `netdev_alloc_cache'. Otherwise disable BH and use `napi_alloc_cache.page'. The IRQ check is cheaper compared to disabling & enabling interrupts and memory allocation with disabled interrupts does not work on -RT. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> 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.